bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractRepeated 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

AbstractThe 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

AbstractVarious 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

AbstractThe 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

AbstractThe 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

AbstractMonophasic 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

AbstractThe 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

AbstractContractions 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

AbstractA 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

AbstractThe 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

AbstractSlices 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

AbstractTwo 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractContractions 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

AbstractThe 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

Abstract“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

AbstractPlasma 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.