bluuebunny/crossref_metadata_2025 huggingface dataset:
Salivary Secretion in the Rat in a Hot Environment
Authors: Elmér Mats , Ohlin Per
Published: December 2008

Conscious rats were found to secrete saliva from the submaxillary gland when exposed to heat. In rats with sympathetically denervated glands the secretory rate was a little lower and in parasympathetically denervated glands the secretion was almost abolished. The salivary flow appeared to increase with increasing ambient temperature and the secretion started earlier at higher temperatures. The secretion elicited by heat stress was compared to the secretion evoked by electrical stimulation of the parasympathetic nerve to the gland. It is concluded that the salivary secretion evoked by heat stress is mainly mediated by the parasympathetic secretory nerves, although the sympathetic fibres also take part.
The Intracellular pH‘ in the Brain in Acute and Sustained Hypercapnia
Authors: Messeter Kenneth , Siesjö Bo K.
Published: December 2008

The regulation of intracellular pH′ in the brain was studied in rats exposed to about 11% CO2 for periods of 15 min to 72 h. At the end of each exposure period cisternal cerebrospinal fluid, as well as the supratentorial parts of the brain, were sampled and analysed for the CO2 contents. The intracellular HCO3‐ concentration was calculated assuming extracellular volumes of 12, 15 and 20%, respectively, and the intracellular pH′ was derived from the HCO3‐ concentration and the mean tissue CO2 tension. Acute hypercapnia (15 min) was associated with an increase in the intracellular HCO3‐ concentration of about 6 meq/kg of i.e. water. With an extracellular volume of 15% the corresponding decrease in pH′i was from 7.06 to 6.93. When the hypercapnia was upheld there was a further increase in the intracellular HCO3‐ concentration of about 5 meq/kg and an increase in pH′i to about 7.03. Most, if not all, of this regulation of pH′i occurred during the first 3 h. An analysis of the regulating mechanisms suggests that physicochemical buffering, metabolic consumption of acids, and transmembrane fluxes of H+ or HCO3‐ each contributed about a third of the total accumulation of bicarbonate in the cell during hypercapnia.
Characterization of Simple and Composite Uptake Systems in Cells and Tissues by Competition Experiments
Authors: Bárány Ernst H.
Published: December 2008

The first step of active uptake of a substance is taken to be the reversible combination with a primary binding site (receptor) by a first order reaction. Such a binding is characterized by an affinity constant. Several kinds of receptors can be simultaneously present in a cell or tissue: one then has a composite uptake system. Each receptor is characterized by an affinity spectrum, a list of its affinities to all possible substances with any affinity. Naturally, such a list can never be complete. The affinity spectrum can be obtained by means of a single test substance which the tissue is allowed to accumulate and which is analyzed in the tissue while the affinities of all other substances are measured by their ability competitively to depress the uptake of the test substance. For these substances, only the concentrations in the medium are required. The mathematics of such competition experiments are derived for a simple and for a composite system consisting of two independent systems with completely overlapping but not identical affinity spectra. A formula is derived which allows one to estimate the affinities of any substance to the two receptor systems by measurements at four concentrations of the substance. In the case of incompletely overlapping affinity spectra, the systems can either be studied separately or as if there were complete overlap.
Uptake of Micellar Lipids by Small Intestinal Segments [under Different Experimental Conditions].
Authors: Sylvén Christer
Published: December 2008

Uptake of radioactive cholesterol, sitosterol and monoolein from micellar solutions was studied under different conditions in rat small intestinal segments both with and without blood supply, and in inverted segments in vitro. The Na+/K+ ratio of the micellar test solution did not influence the uptake of any species of lipid tested. In vivo the uptake of sterols was maximal at 37°C. It had a Q10 of about 3. Three states of sterol uptake were observed. (1) A high uptake of both cholesterol and sitosterol, (2) a low uptake of both sterols, and (3) a low uptake of sitosterol with a high uptake of cholesterol. The latter state corresponds to normal uptake in vivo. These states were demonstrated under different experimental conditions involving exclusion of blood supply to the small intestine, extensive hypothermic treatment of the rat, extensive hypothermic treatment followed by rewarming to 37°C, and biliary drainage followed by uptake experiments with high concentrations of NaTDC or NaTC. It was demonstrated that the normal uptake of sterols could be both irreversibly and reversibly changed into the other abnormal states of uptake.
Uptake of Serotonin in Blood Platelets in vitro. III: Effects of Acetate and Other Monocarboxylic Acids
Authors: Lingjærde O.
Published: December 2008

The chloride‐dependent uptake of serotonin in human blood platelets is stimulated by acetate, maximal effect being obtained with about 10–15 mM acetate at pH 7.3. In the absence of chloride (or other halogen anions), acetate has no effect on serotonin uptake. The stimulatory effect of acetate seems to be mainly due to an increased affinity of the “anionic site” of the 5HT carrier for chloride. Acetate conceiveably reacts with the hypothetical “activating site” on the plasma membrane in the same way as was previously shown to be the case for nitrite. The specific activating effect of both acetate and nitrite is blocked by increasing the extracellular potassium concentration to about 30 mM. At pH 6.2, acetate in concentrations higher than about 10 mM exerts an uncompetitive inhibitory effect on serotonin uptake. This effect is not counteracted by potassium, and seems to be quite independent of the stimulatory effect. The stimulatory effect of acetate on serotonin uptake is shared by other monocarboxylic acids, such as formate, propionate, butyrate, lactate, and pyruvate. The possibility that lactate may act as a physiological regulator of serotonin uptake in platelets and “serotoninergic” neurons is mentioned.
Effect of Training on Oxygen Consumption in Negative Muscular Work
Authors: Klausen K. , Knuttgen H. G.
Published: December 2008

During negative work, bicycling downhill on a motordriven treadmill, it was found in 3 young, male subjects that the oxygen consumption (V̊o2) continued to increase over a 25–50 min exercise period. The increase from the 10th to the last min of exercise was more than 25%. After 3–5 weeks of training with negative work of higher numerical work intensity, a marked decrease in V̊o2 was seen and the continuous increase in V̊o2 during the exercise period was reduced to a minimum, when the subjects worked at the same work intensity as before the training period. The direct employment of energy received by the muscles during negative work in the contraction process is discussed as a possible explanation for the reduced aerobic metabolism. Strengthening of the connective tissue during training and changes in muscle viscosity due to changes in muscle temperature are suggested as other possible factors involved in the decrease in V̊o2.
The Metabolism of Monosaccharides in Isolated Rat Mast Cells and its Influence on Histamine Release Induced by Adenosine‐5‘‐Triphosphate.
Authors: Diamant Bertil , Peterson Curt
Published: December 2008

Histamine release from isolated rat mast cells induced by extracellularly applied ATP in the presence of calcium was enhanced by D(+)glucose and D(+)mannose, but not by D(‐)‐fructose or D(+) galactose (0.6 mM of each). Only those monosaccharides which enhanced the histamine release were metabolized by the mast cells through the Embden‐Meyerhof pathway as judged from the accumulation of lactate in samples incubated with the sugars. Lactate (1 mM) as well as pyruvate (1 mM) also enhanced the histamine release induced by ATP. Antimycin A (10‐7M) completely inhibited ATP‐induced histamine release irrespectively of the presence of glucose, pyruvate or lactate. Iodoacetate (10‐4M) blocked the enhancing effect of glucose, but not that of pyruvate or lactate. In the presence of glucose (0.6 mM) or mannose (0.6 mM) the accumulation of lactate in suspensions of rat mast cells was enhanced by antimycin A (10‐7M) and blocked by iodoacetate (10‐4M). In the absence of glycolytic substrates and metabolic inhibitors no accumulation of lactate was noted whereas in the presence of antimycin A (10‐7M) a slight but statistically significant accumulation occurred.
Effects of Noradrenaline on Activity in Single Aortic Baroreceptor Fibres
Authors: Aars Harald
Published: December 2008

The possibility of sympathetic control of the sensitivity of arterial baroreceptors has been examined by recording activity of single baroreceptor fibres in the rabbit's aortic nerve before and during intravenous infusion of noradrenaline (4–6 μg/kg × min). Activity was related to blood pressure — which could be changed by bleeding and reinfusion of blood — and to diameter of ascending aorta measured with ultrasonic technique inside the intact thorax. At the same blood pressures as in control runs, activity of 34 single myelinated fibres (conduction velocities 10–35 m/s) was lowered by noradrenaline, on average by 1 spike per pulse beat, and diastolic aortic diameter was reduced by about 7%. When compared at equal diastolic diameters, pulsatile diameter variations were smaller with noradrenaline than in control runs, but even so, receptor activity was found to have risen by 2–3 spikes per pulse beat, i.e., up to 50 %. Thinner myelinated fibres (conduction velocities about 5 m/s) occasionally showed higher than normal activity also at comparable blood pressures. The results demonstrate that the sensitivity of aortic baroreceptors to distension of the receptor area can be increased by noradrenaline. However, as aortic diameter is simultaneously decreased, activity in most single baroreceptor fibres was slightly reduced at any given blood pressure during intravenous infusion of noradrenaline.
Differential Effect of Sleep Deprivation on the Two Slow Wave Sleep Stages in the Gat
Authors: Ursin Reidun
Published: December 2008

The effect of total sleep deprivation on the sleep stages and their interrelations was studied in 10 cats. EEG, EMG and eye movements were recorded for 24 h after 12 h and 24 h sleep deprivation and after no sleep deprivation. Sleep was divided into three stages: Light slow wave sleep (LSWS), deep slow wave sleep (DSWS) and rapid eye movement (REM) sleep. The total quantities of DSWS and REM sleep in the 24 h recordings increased with deprivation, as did the relative proportion (per cent of total sleep) of these sleep stages. The total quantity of LSWS did not change with sleep deprivation, and the LSWS per cent of total sleep decreased. The changes were most pronounced after 24 h deprivation and in the first hours of recovery sleep. Sleep deprivation reduced LSWS episode length and tended to increase DSWS and REM sleep episode length. The number of sleep cycles was increased, but the length of each cycle was not altered. The results support earlier findings of a functional dissociation between LSWS and DSWS and a functional relationship between DSWS and REM sleep.
The Distribution of the Yolk Cholesterol in the Young Chick. An Autoradiographic Study
Authors: Svanberg Olof
Published: December 2008

14C‐4‐cholesterol was injected into the invaginated yolks of newly hatched chicks and the distribution of the labelled molecules was recorded by autoradiography. 14C was homogeneously distributed in the yolks 1 h after the injection. After 4 h, traces of radioactivity were found in the liver and after 12 h 14C had been transported from the liver into most parts of the body. The liver content of 14C‐labelled cholesterol was very high up to 6 days after the injection. The bile was rapidly intensively labelled, and was regularly regurgitated into the gizzard. The walls of the large arteries contained significantly more 14C‐cholesterol than the surrounding tissues. Organs engaged in steroid hormone synthesis incorporated more yolk cholesterol than “inactive” tissues. In the central nervous system of the youngest chicks, radioactivity was only found to any great extent in the pineal gland, while the peripheral nerves were rapidly intensively labelled. The retention of 14C‐cholesterol after 2 months was greatest in the peripheral nerves and the white matter of the central nervous system. Starvation did not markedly influence the relative distribution pattern of labelled material during the first week after hatching.
Properties of Hematopoietic Progenitor Cells
Authors: Benestad Haakon Breien , Breivik Harald
Published: December 2008

Assay of hematopoietic progenitor cells has been carried out with the use of quantitative diffusion chamber culturing. Some progenitor cell properties were investigated. Hydroxyurea, which kills the fraction of normal mouse bone marrow progenitor cells synthesizing DNA, was given to donor mice of different ages. This DNA‐S fraction of progenitor cells was found to be as large as or larger than the corresponding fraction of spleen colony‐forming cells. It was concluded that the progenitor cells for the formation of granulocytes in the chambers are probably mixtures of cells which can give rise to spleen colonies and of cells able to form agar colonies.

In chamber cultures, formation of granulocytes and macrophages is prominent, whereas erythropoiesis is scant or absent. This differentiation pattern was not changed by adding erythropoietin to the culture inocula. Nor did admixture of antigens to the cell inocula influence the formation of granulocytes and macrophages. The chamber progenitor cell population as a whole was found to have a near average adhesiveness to glass and fibrin, when compared with normal bone marrow cells or blood leucocytes.
Relationship between Antral Acidity and Gastrin Releasing Potency of Chemical Stimulants
Authors: Andersson Sven , Elwin Carl‐Eric
Published: December 2008

The effect of antral acidity on gastrin releasing potency of some compounds was studied in Pavlov and Heidenhain pouch dogs. Gastrin release by an unionized stimulatory compound (ethanol) was less sensitive to changes of pH than that by ionized compounds (choline, acetylcholine) or a compound with amphoteric characteristics (glycine). All dogs showed pronounced signs of general, cholinergic activation with the highest concentration of choline at pH 7 in the dose‐response curve indicating absorption through the antral mucous membrane. Absorption of choline showed pH dependency and no signs of cholinergic excitation were obtained at pH 5 or below. At low pH levels (pH 1–2) acid may produce a general, physiological insensitivity of the gastrin release mechanism to all stimuli and at higher pH levels the action of acid most likely includes effects related to changes of ionization and absorption of stimuli. In comparison with maximal acid output to intravenous histamine, choline was found to be the most potent compound under study. Responses to 4 % choline solutions at pH 7 reached the same level and responses at pH 5 exceeded the maximal histamine response. Responses to acetylcholine and glycine were 60–65 % of maximal histamine response at the most, whereas acid output to antral irrigation with ethanol only reached 1/3 of the maximal histamine response.
Endogenous Inhibition of the Mechanical Response of the Isolated Rat and Guinea‐Pig Vas Deferens to Pre‐ and Postganglionic Nerve Stimulation
Authors: Swedin Göran
Published: December 2008

Repeated periods with prolonged nerve stimulation (30 s) of the isolated vas deferens tended to depress especially the initial, rapid phase of subsequent contractions.

The following findings led to the conclusion that the inhibition was induced by prostaglandin (PG)‐like material, released from the organ on nerve stimulation: 1. The inhibition was immediately abolished on washing of the organ. 2. It appeared faster in an organ bath of small volume than in one of a greater. 3. It was possible to transfer the substance from one bath to influence an organ in another. 4. The inhibitory agent, like exogenous PG, influenced both phases of contraction, the second, however, to a less extent. 5. The ganglionic transmission in the last part of the hypogastric nerve was found to be extremely sensitive to the inibitory substance as to exogenous PG (0.1–0.4 ng/ml). 6. In vitro inihibition of PG synthesis led to a partial or total abolishment of the endogenous inhibition. 7. Release upon nerve stimulation of PG‐like material, mainly PGE2, was established.

It is suggested that this endogenous inhibiting process might play a modulating role in the nerve‐induced mechanical activity of this organ also under in vivo conditions.
Influence of Synthesis and Membrane Pump Inhibition on the Nerve Impulse Induced Disappearance of Noradrenaline from Rat Salivary Glands
Authors: Almgren Olle
Published: December 2008

The cervical sympathetic trunk of rats was unilaterally stimulated with 5 imp/s for different time intervals up to 3 h and the contraction response of the lower eye‐lid was recorded. At the end of the stimulation the content of endogenous noradrenaline (NA) and previously administered dl‐3H‐NA was measured in the submaxillary + sublingual glands. For inhibition of the NA synthesis 500 mg/kg DL‐a‐methyl‐p‐tyrosine methylester (H 44/68) was given to one group of rats and for blocking the recapture of NA into the nerve endings protriptyline (initially 10 mg/kg) was administered to some other rats. Also, some rats received both drugs. In untreated rats3H‐NA disappeared faster than endogenous NA following nerve stimulation while after synthesis inhibition no difference in disappearance rate was found between tritiated and endogenous NA. The contraction response of the lower eye‐lid was gradually reduced after synthesis inhibition while it remained essentially unchanged throughout the experiment in the untreated animals. The data suggest that the amount of immediately available transmitter decreases during stimulation after inhibition of the NA synthesis, resulting in a reduced transmitter output per stimulus and hence in a reduced effector response. The retarded disappearance of3H‐NA seen after protriptyline treatment could also be explained by a reduced output per stimulus but other possibilities may also exist.
Differences in the Antidiuretic Response to Intracarotid Infusions of Various Hypertonic Solutions in the Conscious Goat
Authors: Eriksson L. , Fernández O. , Olsson K.
Published: December 2008

Various hypertonic equi‐osmolal solutions were infused via permanently implanted catheters into the external carotid artery of conscious, hydrated goats. The infusions (1.5 ml/min) of 1 M NaCl, 2 M fructose and 2 M sucrose caused a marked inhibition of the water diuresis. The effect was evidently due to a release of antidiuretic hormone (ADH) since it disappeared after induction of diabetes insipidus. No antidiuretic response occurred during infusions of either 2 M glycerol or 2 M galactose, while a weak response was seen after infusions of 2 M glucose. Infusions of 2 M urea gave inconsistent results. Infusions of hypertonic fructose into the 3rd ventricle of the hydrated goat did not change the course of the water diuresis, whereas the corresponding infusion of equi‐osmolal NaCl effectively released ADH. It is concluded that neither changes in the blood osmolalities as such, nor different penetration rates across the blood‐brain barrier can explain the results, some of which appear incompatible with the current osmoreceptor theory.
Effect of d‐Ainphetamine on Spontaneous and Stimulation‐Induced Release of Catecholamines
Authors: Farnebo Lars‐Ove
Published: December 2008

The effect of d‐amphetamine on the uptake, spontaneous release and stimulation‐induced release of catecholamines (CA) in central and peripheral tissues was investigatedin vitro.d‐Amphetamine was most potent to cause release of extragranularly located CA, taken up after pretreatment with reserpine and nialamide. In agreement with previous investigations, it is concluded that this effect is probably mainly responsible for the well‐known central stimulating action of the drug at low doses. About ten times higher concentration was needed to reduce uptake and retention of CA in tissues of untreated rats. At about the same concentration increase of the stimulation‐induced tritium overflow was obtained both from NA and DA nerve terminals. This increase might contribute to the CA depletion caused by high doses of d‐amphetaminein vivo.Spontaneous CA release from tissues of untreated rats was affected only at a high concentration.
Left Ventricular Receptors Activated by Severe Asphyxia and by Coronary Artery Occlusion
Authors: Thorén Peter
Published: December 2008

The activity in unmyelinated afferents from left ventricular receptors was examined in cats during shortlasting general asphyxia and during transient occlusion of one coronary artery. After 40–70 s of asphyxia the receptors increased their activity. The firing initially displayed a cardiac rhythm but became continuous when the asphyxia was prolonged and intensified. This increased activity was closely related to a mechanical distension of the left ventricle when the nutritional supply was compromised suggesting a mechanoreceptor rather than a chemo‐receptor function of the recepton. Coronary occlusion also caused an activation of the ventricular receptors after a latency of about 35 s with an initial cardiac rhythmicity which became continuous with prolonged occlusions. The receptor activation appeared also in this situation to be caused by the mechanical bulging of the ischemic area of the left ventricular wall, rather than by chemical factors.
Studies on Myocardial Excitation of the Right Ventricle of the Dog Heart in Situ
Authors: Samuelsson R. , Sjöstrand U.
Published: December 2008

Monophasic action potentials (MAP) were recorded by a suction electrode catheter which was pushed against the endocardial side of the free wall of the right ventricle in the dog heart in situ. The spatial and temporal distributions of the depolarization and repolarization processes were studied. The durations of the MAP recorded from different subendocardial areas of the ventricular wall showed no systematic differences. The excitation process spiead radially from the prepapillary region. During stimulation of the vagal nerves no change of the impulse propagation velocity or of the shape and duration of the MAP was observed. On endocardial, unipolar pacing in the prepapillary region of the right ventricle the excitation process in the free ventricular wall corresponded closely to that noted on spontaneous excitation; this electrode position also gave the shortest Q‐T interval.
The Fine Structure of the Paracervical (Frankenhauser) Ganglion of the Rat after Permanganate Fixation
Authors: Hervonen Antti , Kanerva Lasse , Teräväinen Heikki
Published: December 2008

The fine structure of the paracervical ganglion was studied in the rat after 3 % KMnO4 fixation. Three types of neuronal cells were observed: (1) The majority of cells were devoid of dense‐core vesicles (DCV). (2) The minority of cells with typical neuronal structure contained small (500 A) and large (1000 A) DCV. (3) The cells resembling those of the adrenal medulla contained vesicles up to 3000 A in diameter with irregular and dense core. The synaptic axon terminals to the different cell types contained agranular vesicles. Because no small DCVs were found, these synapses are presumably not adrenergic.
Cholecystokinetic Effect and Concentration of Cyclic AMP in Gall‐bladder Muscle in vitro
Authors: Andersson Karl‐Erik , Andersson Rolf , Hedner Pavo
Published: December 2008

Contractions were induced by the synthetic C‐terminal octapeptide of cholecystokinin (C8‐CCK) in strips of guinea pig gall‐bladder in vitro. These contractions were relaxed by cyclic AMP (CAMP) and by agents known to increase the intracellular content of cAMP (isoprenaline and theophyllamine). The contractile response to C8‐CCK was preceded by an almost 50 per cent activation of the phosphodiesterase activity and a 67 per cent decrease of the cAMP content in the muscle. It is concluded that C8‐CCK lowers the content of cAMP in the guinea‐pig gall‐bladder muscle by activating phosphodiesterase. This metabolic response to C8‐CCK may be of importance for the development of the contractile activity.
The Effects of Vasoconstrictor Fibre Stimulation on the Consecutive Vascular Sections of the Small Intestine of the Cat during Prolonged Regional Hypotension
Authors: Haglund Ulf , Lundgren Ove
Published: December 2008

A plethysmographic technique was used on the cat to investigate the effects of electrical stimulation of the regional sympathetic vasoconstrictor fibres on intestinal consecutive vascular sections during prolonged hypotension at approximately 55 or 30 mm Hg produced by graded arterial occlusion. The initial peak resistance and the capacitance responses declined continuously throughout the hypotensive period, the rate of decline being higher the lower the per‐fusion pressure. After 2.5 h hypotension at 30 mm Hg the nervous vasoconstrictor effects on the resistance and capacitance vessels amounted to 50 and 30 per cent of control, respectively. The reactivity of the precapillary sphincters as reflected in the capillary filtration coefficient (CFC), was largely unaltered during the hypotension at the 55 mm Hg level. At the lower perfusion pressure a marked increase of CFC was noted between and during nervous stimulations. Mean capillary hydrostatic pressure was not significantly changed by nervous activation, hut seemed to increase in the latter half of most experiments at 30 mm Hg. When releasing the arterial clamp after a 30 mm Hg hypotension the whole cardiovascular system seemed to derange progressively. Mucosal ulcerations and bleedings were regularly found in all these animals.
The Influence of Contraction Frequency and of a Local Anesthetic (Mepivacaine) on Human Fetal Myocardium
Authors: Gennser Gerhard , Jóhannsson Magnús , Nilsson Erik
Published: December 2008

The relation between contraction frequency and mechanical performance was investigated in isolated perfused heart preparations and in papillary muscles from human fetuses at mid‐gestation. The influence of mepivacaine on the isometric force and the action potential of the papillary muscles and on the contractility of the whole hearts was also studied. Under the experimental conditions used, the isometric force of the papillary muscles increased with frequency within the range 60 to 180 contractions per min. The right intraventricular pressure of the isovolumetrically contracting hearts was influenced only to a minor degree by changes in contraction rate between 60 and 150 contractions per min and decreased at higher frequencies. Mepivacaine (0.625–10 μg/ml) caused a dose‐dependent decrease of the active force and a slight reduction of the duration of the action potential in the papillary muscle. The effects of contraction frequency and of mepivacaine are discussed in relation to the asynchrony of the ventricular contraction.
Inhibition by Hippurate and Probenecid of in vitro Uptake of Iodipamide and o‐Iodohippurate. A Composite Uptake System for Iodipamide in Choroid Plexus, Kidney Cortex and Anterior Uvea of Several Species
Authors: Bárány Ernst H.
Published: December 2008

Slices of kidney cortex and liver, pieces of lateral choroid plexus and of ciliary body with or without iris were incubated in a potassium‐rich medium containing labelled iodipamide often together with labelled o‐iodohippurate. Tissues were from rabbits, guinea‐pigs, monkeys (3 species), dogs, cats and chicken. Iodipamide at 0.5—2 μM depresses uptake of labelled iodipamide by rabbit kidney cortex wthout affecting uptake of o‐iodohippurate. Hippurate at 30 mM suppresses uptake of o‐iodohippurate in all tissues tested but leaves a fraction of iodipamide uptake in all tissues and species tested. The findings with o‐iodohippurate uptake are compatible with a single uptake system, the findings with iodipamide and the kinetics derived for this substance are incompatible with a single uptake system. Iodipamide seems to be accumulated by one hippurate‐sensitive system shared with o‐iodohippurate and at least one other, hippurate‐insensitive system. This latter system usually is a minority system in kidney cortex and anterior uvea but dominates in liver and choroid plexus and in cat kidney cortex. The hippurate‐insensitive system can be suppressed by probenecid but needs a higher concentration than the hippurate‐sensitive one.
A Comparison of Renal Function in Rats Anesthetized with Inactin and Sodium Amytal
Authors: Elmer Mogens , Eskildsen Peter C. , Kristensen LarsØstergaard , Leyssac Paul P.
Published: December 2008

Two distinctly different renal functional states were obtained in parallel series of non‐diuretic rats anesthetized with Amytal and Inactin, respectively.

In the Amytal series proximal reabsorption rates ranged from 0.34 to 1.19 ml.min‐1· g KW‐1 (mean value 0.72 ml.min‐1· g KW‐1). The reciprocal of the occlusion time (1/OT) and of transit time (1/TT) increased in direct proportion to the inulin clearance (ClIN) indicating that proximal luminal diameter remained unchanged over the “spontaneous” range of values. Proximal as well as distal reabsorption rates were independent of serum‐ and tissue Amytal concentrations while proximal reabsorption rate was inversely correlated with log renin activity of serum.

In the Inactin‐series proximal reabsorption rate was depressed and ranged from 0.20 to 0.74 ml.min‐1· g KW‐1 (mean value 0.46 ml.min‐1· g KW‐1). 1/OT and 1/TT was constant indicating a direct relationship between luminal diameter and ClIN. Proximal reabsorption rate was inversely correlated with serum Inactin concentration, while no relationship between proximal reabsorption rate and log renin activity was apparent.

It is concluded that the variation in proximal reabsorption rate (and filtration rate) observed in Inactin anesthetized rats is induced by the anesthetic which in some way limits the reabsorption rate. The variation observed in Amytal anesthetized rats, on the other hand, is “spontaneous”, i.e. the rate is limited by factors other than the anesthetic.
Facilitation from Ipsilateral Primary Afferents of Interneuronal Transmission in the Ia Inhibitory Pathway to Motoneurones
Authors: Fedina L. , Hultborn H.
Published: December 2008

The effects on transmission in the Ia inhibitory pathway to motoneurones by volleys in ipsilateral primary afferents were investigated with intracellular recording from motoneurones. In spinal cats under chloralose anesthesia Ia IPSPs in flexor as well as extensor motoneurones were regularly facilitated by volleys in cutaneous, high threshold muscle and joint afferents. In decerebrate cats with a low pontine lesion IPSPs were not facilitated from high threshold muscle and joint afferents, although volleys in low threshold cutaneous afferents evoked a facilitation also in this preparation. It is postulated that the Ia inhibitory interneurones receive excitatory actions from the ipsilateral flexor reflex afferents (transmission depressed in the decerebrate state) and through a separate pathway from low threshold cutaneous afferents. The recurrent effects from motor axon collaterals were investigated on inhibitory transmission to motoneurones from different afferents. A strong positive correlation was revealed between recurrent depression of IPSPs evoked from different afferents and facilitation of Ia IPSPs by the same afferent volleys. This suggests that the recurrent depression of IPSPs from different primary afferents depends on an excitatory convergence from them onto the Ia inhibitory inter‐neurones, which mediate at least part of the IPSP evoked in the motoneurone from these afferents.
Shunting by Diffusion of Inert Gas in Skeletal Muscle
Authors: Sejrsen Per , Tønnesen K. H.
Published: December 2008

The isolated cat gastrocnemius preparation was used to study shunting by diffusion of133Xenon from arterial to venous blood.133Xenon in saline,51Chromium‐labelled erythrocytes, and T1824‐albumin were mixed and injected as a bolus into a side branch of the femoral artery. The muscle was autoperfused and stimulated electrically. Gas tight samples were taken every 0.7 to 1.0 s with a special technique developed for this purpose. The effluent blood from the muscle was collected in a 1.5 m long glass tube (i.d. 2 to 3 mm), and from a side branch at the inflow end of the tube mercury drops were led into the tube dividing the blood stream into samples. The inflow was stopped after 20 seconds and the contents of the two isotopes in the samples were measured by collimated counting externally over the tube. The T1824‐analysis were performed spectrophotometrically.133Xenon appeared in the venous samples before the intravascular reference tracers indicating that133Xenon was shunted by diffusion from arterial to venous blood. The fraction of133Xenon shunted by diffusion was estimated to about 11 per cent.
In Vitro Work Load and Rat Heart Metabolism
Authors: Hjalmarson Ake , Isaksson Olle
Published: December 2008

The isolated working rat heart preparation was used to study the effects of well defined work loads on heart protein synthesis. The rate of protein synthesis was evaluated by measuring the incorporation rate of phenylalanine‐3H into whole heart protein. Increased pressure load (afterload) accelerated the protein synthesis. A stimulatory effect was demonstrated with glucose or palmitate as substrate and with 1 or 5 times the normal rat plasma levels of all amino acids in the perfusion medium. The protein synthesis of both control and overloaded hearts was significantly accelerated with palmitate as substrate or with high levels of all amino acids. The work load effect could, thus, be obtained under conditions optimal for heart protein synthesis in vitro. In contrast to the stimulatory effect of in‐creased afterload the rate of protein synthesis was not changed when the left atrial filling pressure (preload) was increased, although the external heart work was raised several times. End systolic volume was markedly increased in pressure overloaded hearts compared to hearts perfused under control conditions or with increased preload. It is concluded that an increase in contractile tension during systole and/or an increase in the end systolic volume was a necessary requirement for the acceleration of protein synthesis.
Force and Contraction Velocity of the Middle Ear Muscles in the Gat and the Rabbit
Authors: Teig E.
Published: December 2008

Contractions of the stapedius and the tensor tympani muscles in cats and rabbits have been elicited at controlled length by electric stimulation of their motor nerves at varying stimulus frequencies. Both muscles were stronger than found in previous investigations. The tetanic tension of the stapedius was an average of 13.9 g (cat) and 15.4 g (rabbit). The tetanic tension of the tensor tympani averaged 54.3 g (cat) and 32.3 g (rabbit). By comparing the data from cats with the findings of Wever and Bray (1937, 1942) each muscle developed sufficient tension to cause a reduction in the sound transmission of the middle ear of more than 20 dB. With a twitch contraction time between 20 and 30 ms both muscles must be classified as fast muscles. However, different degrees of submaximal stimulation gave evidence for an additional slow twitch component in the tensor tympani muscle.
Tension and Contraction Time of Motor Units of the Middle Ear Muscles in the Cat
Authors: Teig E.
Published: December 2008

The all‐or‐none contraction of 46 individual tensor tympani motor units and of 44 individual stapedius motor units in response to threshold stimulation of their motor neurones have been recorded. The tensor tympani was found to contain two types of twitch motor units, a fast type and a slow type. The fast type had a contraction time between 23 and 40 ms, a half relaxation time between 17 and 46 ms and a tetanic fusion rate of 75 Hz. The slow type had a contraction time between 58 and 92 ms, a half relaxation time between 52 and 100 ms and a tetanic fusion rate of 15 to 20 Hz. The stapedius muscle consisted of only one type of twitch motor units, a fast type with contraction time from 14 to 39 ms, a half relaxation time from 15 to 50 ms, and a tetanic fusion rate between 75 and 100 Hz. The number of motor units was estimated as the ratio between the average twitch tension of the muscles to supramaximal stimulation and the average twitch tension of individual motor units. On the average, the tensor tympani contained 92 fast and 40 slow twitch motor units and the stapedius 87 fast twitch motor units.
Estimation of Alveolar Po2
Authors: Rosenhamer Gunnar
Published: December 2008

“Mean alveolar” Po2 calculated from the alveolar gas equation, using arterial PcO2, was compared with the corresponding end‐expired PO2, measured with a rapidly responding O2 electrode (τ= 0.05 si and with arterial Po2. 12 healthy subjects (WO2max 1.8–3.6 1/min) were studied at rest supine and during rest and exercise in the sitting position, breathing air and 12 %O2. Differences between end‐expired and mean alveolar Po values were small and statistically insignificant during exercise while breathing air and during hypoxia at rest, both sitting and supine. Exercise during hypoxia resulted in lower end‐expired than mean alveolar values. At rest breathing air the end‐expired values were higher, especially in the sitting position (12 mm Hg). The results are compatible with the assumption of non‐synchronous emptying of alveoli, combined with exercise‐ and gravity dependent regional differences in alveolar PO2‐ From simultaneous measurements of arterial Pco2 it is inferred that the end‐expired Po2 approximates the time‐ and volume weighted mean of alveolar Po2 only at high rates of exercise, breathing air.
Correlation between Hyperinsulinemia and Hyperphagia in Rats with Ventromedial Hypothalamic Lesions
Authors: Hustvedt B. E. , Løvø A.
Published: December 2008

Plasma levels of immunoreactive insulin (IRI) and glucose were determined in unrestrained rats equipped with chronically implanted venous catheters. Electrolytic lesions were then placed bilaterally in the ventromedial hypothalamic area. Food intake was restricted in order to prevent hyperphagia. A 60–280 % increase in the IRI level with a concomitant small increase in blood glucose was demonstrated on the second day post‐operatively. The animals were then given free access to food. The gain in body weight during the following 3 days of ad lib feeding and the post‐operative increase in the IRI level of each animal was positively correlated.
The Tissue Distribution of 3H‐Terbutaline (Bricanyl®) in Mice
Authors: Bodin N. O. , Hansson E. , Ramsay C. H. , Ryrfeldt Å.
Published: December 2008

The tissue distribution of 3H‐terbutaline. a new β‐stimulaing tagent, was investigated in mice by whole‐body autoradiography as well as by determinations of unchanged and biotransformed terbutaline in serum, lung, heart, and liver.

The radioactivity was localized mainly to the extracellular space and the levels in most tissues were of the same magnitude as that in blood; no uptake and storage of the drug was observed. Neither terbutaline nor its metabolites penetrated the blood‐brain barrier or the placenta barrier. High relative concentrations of unchanged drug were found in the tissues studied, especially in the lung. A low rate of biotransformation is considered to be the cause for this.
The Volume Responses of Various Vascular Beds to a General Blood Loss. A Study Carried out in Rats Exposed to Two Different Procedures of Anesthesia
Authors: Aarseth P. , Piene H.
Published: December 2008

Several vascular compartments have been claimed to have marked blood depot functions. In the present experiments an attempt has been made to compare different vascular beds of the rat in this respect, by evaluating the tissue blood content in bled and non‐bled animals. Erythrocytes and plasma‐albumin were labelled by radioisotopes, and the whole rat was then immersed in liquid nitrogen. The lungs, the heart with the thoracic vessels, the splanchnic organs and samples from skeletal muscles were then removed and their content of radioisotopes estimated. In animals anesthetized intraperitoneally with pentobarbitone the pulmonary blood volume and the skeletal muscle blood content were markedly reduced after a blood loss of 12 % When, however, the animals were anesthetized by ether‐inhalation, and by a subsequent small dose of pentobarbitone i.v., then a similar bleeding caused a marked reduction in the splanchnic blood volume, but almost no reduction in the pulmonary blood volume or the skeletal muscle blood content.
Effect of Brain Lesions and Chlorpromazine on Accumulation and Disappearance of Catecholamines Formed in vivo from14C‐Tyrosine
Authors: Nybäck Henrik
Published: December 2008

Rats were subjected to a unilateral stereotaxic lesion at the level of the mesencephalic‐hypothalamic junction where the nigro‐striatal dopamine (DA) pathway is known to pass. Between 6 and 18 h after the lesion the level of DA in the striatum on the same side was increased by about 50 per cent. Between 18 and 48 h after the lesion the content of DA declined to 15 per cent of that of the contralateral striatum and stayed at this low level during the following 6 days. The content of noradrenaline (NA) tended to be increased 24 h after the lesion but no change was found on the following days. The accumulation and disappearance of14C‐DA formed from14C‐tyrosine in the striatum 12–24 h after the nigral lesion were decreased on the lesion side in comparison with the contralateral side. The accumulation and disappearance of14C‐NA did not differ between the 2 sides. Chlorpromazine accelerated both accumulation and disappearance of14C‐DA in the striatum on the side contralateral to the lesion but not in the striatum of the lesion side. In animals with a unilateral lesion above the DA pathway, in the posterior thalamus, chlorpromazine accelerated the accumulation of14C‐DA on both sides. The accumulation of14C‐XA in the striatum was increased by chlorpromazine on the intact side following both types of lesions. The disappearance of14C‐NA, however, was not influenced by the drug. The results are taken as evidence that chlorpromazine accelerates DA turnover in the striatum by activating the nerve impulse flow in the nigro‐striatal DA pathway.
Splenic Blood Flow in the Guinea‐Pig Measured with Xenon 133, and Calculation of the Venous Output of Lymphocytes from the Spleen
Authors: Sandberg Göran
Published: December 2008

Splenic blood flow was measured in normal guinea‐pigs of three weight classes, and in groups immunized with pertussis vaccine or sheep erythrocytes (SRBC). The determination was based on the wash‐out of xenon 133 injected directly into the splenic tissue.

In the normal guinea‐pigs the blood flow in ml/g min decreased slightly with weight, the means in the three weight classes being 0.85, 0.73 and 0.66 ml/g min. After injection of pertussis vaccine the splenic blood flow was significantly greater in relation to the weight of splenic tissue than for the controls given a saline injection, but the flow was unaffected by immunization with sheep erythrocytes.

Combination of the blood flow values with the differences in lymphocyte content between splenic efferent and afferent blood made it possible to calculate the splenic release into the blood of lymphocytes formed in the spleen. This increased with body weight, and in the heaviest animals reached about 10o cells/24 h. In the animals injected with pertussis vaccine the number of lymphocytes released was significantly greater than in the corresponding controls. An increase recorded after immunization with sheep erythrocytes was, however, not statistically significant.
Effect of Nerve Stimulation In Vitro on the Noradrenaline Content of the Rat Vas Deferens in the Presence of Inhibitors of Noradrenaline Uptake and Synthesis
Authors: Swedin Göran
Published: December 2008

Isolated rat vas deferens preparations were intermittently field stimulated (30 s every min) for 2 or 4 h at 7 or 25 imp/s. At the low stimulation frequency only a very small reduction (7 %) of the endogenous noradrenaline (NA) stores was seen during 4 h stimulation while it was about 15%after 2 h and 37%after 4 h at 25 imp/s. Addition of drugs known to inhibit NA synthesis (a‐methyl‐p‐tyrosine, a‐MPT, 4times10‐4M) or uptake (cocaine, 10‐5M) did not apparently influence neither the spontaneous nor *the nerve‐induced reduction of the endogenous NA stores. The present results seem to support the hypothesis that the functional transmitter pool of the short adrenergic neurons of the vas deferens is very small, and that the residual NA reuptake and synthesis after pharmacological blockade, together with minute refilling from the large storage pools, are able to maintain transmitter homeostasis without significant changes of the total endogenous NA content of the vas deferens.
The Distribution of Xe‐133 in the Left and Right Ventricular Walls of Dog Hearts after Left Ventricular Bolus Injection
Authors: Bagger Henning
Published: December 2008

Bagger, H. The distribution of Xe‐133 in the left and right ventricular walls of dog hearts after left ventricular bolus injection. Acta physiol. scand. 1972. 84. 275– 283.

Regional coronary blood flow was estimated in dogs by counting the activity in tissue blocks of the left and right ventricular walls after bolus injection of Xe‐133 into the left ventricular cavity.

Myocardial uptake of the isotope was 1.7 times higher in the left than in the right ventricular wall, while comparison of the activities in the subepicardial half of the walls showed a ratio left/right of 1.5.

The transport through the endocardial surface of the left ventricular wall was measured during constriction of the left coronary artery. Xe‐133 penetrates to a depth of 7 mm, indicating that transport across the endocardial surface might contribute to the activity of the subendocardial half of the wall.

In the left ventricle the activity was higher (15 %) in the subendo‐ than subepicardial half of the wall, but in view of the transport across the endocardial surface, the amounts of xenon transported by the coronary arteries seem to be equal, indicating a uniform perfusion of the left ventricular wall. No differences appeared either between areas supplied by the anterior descending and circumflex branches of the left coronary artery or between the apex and the base.

In the right ventricular wall there was no difference between subepi‐ and subendocardial activity.
Circulatory Control via Vagal Afferents
Authors: Gastenfors Jan , Knutsson Evert , Sjöstrand Torgny
Published: December 2008

Castenfors, J., E. Knutssonand T. Sjöstrand. Circulatory control via vagal afferents. II. Effects of hemorrhage on afferent discharges via the laryngeal communicans in the rat. Acta physiol. scand. 1972. 84. 355–365.

Recordings were made of afferent impulses passing through the communicating branch between the superior and inferior laryngeal nerves and in the recurrent nerve after section of the vagus. Two types of discharges varying with changes of the blood volume were recorded.

1. Continuous nerve impulses which are increased in frequency on hemorrhage.

2. Repetitive burst of spikes with a heart rhythm which starts at the first heart sound, proceeds until shortly after the P wave and ceases with the IV sound. This activity appears to correspond to the inflow of blood to the heart. On hemorrhage the activity diminishes and disappears entirely after a given loss of blood, returning on reinfusion.

The slowing of the heart rate on hemorrhage, described in the preceding paper, is assumed to be a result of an increase of the impulse flow through the laryngeal communicans. It is also assumed that the allied receptors are located on the low‐pressure side. The receptors firing synchronously with the heart rhythm are assumed to belong to the earlier described group of atrial receptors of type B. Their function is postulated to be opposite to that of the former receptors, thus increasing the heart rate with increasing central blood volume.