bluuebunny/crossref_metadata_2025 huggingface dataset:
Facilitation and Inhibition of Facial Reflexes in the Cat Induced by Peripheral Stimulation
Authors: Lindquist Christer
Published: December 2008

The effects of conditioning peripheral stimuli on reflexes elicited in m. caninus and m. orbi‐cularis oculi by tap stimulation of the facial skin have been studied in cat. Following a conditioning facial skin tap the reflex transmission was facilitated for some 20 ms and this facilitation was succeeded by a period of reflex depression lasting up to 400 ms. A similar type of interaction was observed when the conditioning stimulus consisted of afferent volleys in the lingual or the hypoglossal nerve. Reflex depression of several hundred ms duration resulted when conditioning volleys were elicited in group II afferents in the radial nerve or in afferents of the saphenous nerve.—I. v. injections of strychnine resulted in considerably diminished inhibitory effects of conditioning facial taps which was taken to indicate that postsynaptic mechanisms are involved in the inhibitory reflex control. The reflex depression induced by activity in radial nerve afferents was not affected by strychnine injections to the same extent. It is suggested that the time course of the facial reflex inhibitions indicates involvement of presynaptic inhibition as well.—In the chloralose‐anesthetized cat the blink reflex was suppressed to a considerable degree when elicited at a frequency of 4/s and was almost abolished at 10/s. This “reflex fatigue” was not changed by decerebration. It is suggested that presynaptic inhibitory mechanisms account for the fatiguability of the blink reflex.
Analysis of Facial Reflex Facilitation and Inhibition by Microelectrode Recording from the Brain Stem
Authors: Lindquist Christer
Published: December 2008

The response in the facial nucleus to stimulation of peripheral facial and trigeminal nerve branches is described. After antidromic invasion the excitability of facial motoneurons was lowered for up to 30 ms before as well as after intravenous injections of strychnine. The depression following antidromic stimuli is thus not caused by postsynaptic inhibition of the Renshaw type but rather by positive afterpotentials in the motoneurons. Synaptic activation by tap stimulation of the face led to increased motoneuron excitability setting in after a latency of 3 ms and lasting for 30 ms. This was followed by a lowered excitability lasting for an additional period of 65 ms. The period of depression was presumed to be due to postsynaptic inhibition of motoneurons. The changes of the excitability of facial motoneurons following synaptic activation explain in part previously observed effects of conditioning afferent stimuli on facial reflexes.‐Responses to electrical stimulation of facial and hypoglossal nerve afferents were recorded from reticular neurons. These neurons responded to single stimuli with a repetitive high‐frequency discharge related to the stimulus strength and could respond to an afferent inflow from large areas of the body and limbs. It is discussed whether these reticular neurons may be interneurons in a system exerting inhibitory control of facial muscle reflexes.
The Effect of Calcium on the Potassium Permeability in the Myelinated Nerve Fibre of Xenopus Laevis
Authors: Brismar Tom , Frankenhaeuser Bernhard
Published: December 2008

The effect of changes in the external calcium concentration (in the range from 0.27 to 109 mM) on the potassium permeability mechanism has been investigated with potential clamp technique. An increment in [Ca] was associated with a positive shift along the potential axis of the curve relating the potassium permeability variable (nm) to the membrane potential. This shift varied between 3 mV per e‐fold change in [Ca] at low concentrations and 10 mV in the range of high [Ca]. Changes in magnesium concentration were associated with a similar shift.
Thermoregulation during Positive and Negative Work at Different Environmental Temperatures
Authors: Nielsen Bodil , Nielsen S. Levin , Petersen F. Bonde
Published: December 2008

Cardiac output, and thermoregulatory reactions were studied at 20°, 30° and 35° C during positive work (pos I) and negative work (neg) at O2‐uptakes of 0.8 l/min, and also during positive work (pos 11) at an O2‐uptake of 1.7 1/min). i.e. with a total heat production equal to that during the negative work. At equal O2‐uptakes the cardiac output (Q) was the same in pos I and neg. The blood flow in the working muscles, estimated with a 133Xe method, was not measurably different in pos I and neg. The upper limit for thermal equilibrium was reached at lower environmental temperature in negative work. This is most probably explained by the higher skin circulation during negative work. Since the total Q and muscle blood flow is the same in pos I and neg the blood reserve available for heat transport during external heat stress, e.g. in splanchnic organs is presumably reduced in negative work.
Fluid Transfer between Blood and Tissues during Exercise
Authors: Lundvall J. , Mellander S. , Westling H. , White T.
Published: December 2008

During 6 min exercise on a bicycle ergometer the volume of the leg in normal males increased so as to indicate, after correction for increased regional blood volume, an average trans‐capillary fluid loss into the leg muscles of 19, 31, and 45 ml/kg tissue at light (300 kpm/min), moderate (900 kpm/min), and heavy (1200–1500 kpm/min) work load. The total fluid loss into the active muscle mass was calculated to comprise about 1100 ml during heavy work. Since the concomitant decrease of plasma volume was 600 ml, it follows that some 500 ml of fluid must have entered the circulatory system during the work. The study indicated that this compensatory fluid gain was accomplished by absorption of extravascular fluid from inactive tissues and partly caused by osmosis resulting from work induced arterial hyperosmolality (average increase 22 mOsm/kg H2O). Fluid absorption from inactive tissues was studied in experimental animals during exercise and in resting humans during arterial hyperosmolality produced by intravenous hypertonic infusions. The investigations suggested that at least half of the fluid gain to the circulatory system in heavy exercise could be ascribed to the increased arterial osmolality and the remainder to a reflex decrease of capillary pressure.
The Effects of Intraperitoneally and Intravenously Administered Pentobarbitone Anesthesia on Pulmonary and Splanchnic Blood Volumes in Rats. An Evaluation Carried out before and after Standardized Blood Losses
Authors: Aarseth P.
Published: December 2008

Pulmonary and splanchnic blood volumes have been examined with the use of suitable radioactive isotopes in rats anesthetized with either intraperitoneally or intravenously administered pentobarbitone (30 mg/kg b.w.). The blood volumes in the two vascular areas were evaluated both in non‐bled rats and in animals which had been exposed to a 12 % or a 24 % reduction of the total blood volume. Organ blood content was examined after sudden circulatory arrest which was achieved by rapid freezing of the whole animal in liquid nitrogen. I. p. anesthetized non‐bled rats had a smaller splanchnic blood volume and a larger pulmonary blood volume than the i.v. anesthetized rats. The large lung blood volume of i.p. anesthetized rats was markedly reduced upon a 12 % blood loss. A 24 % blood loss caused moderate additional pulmonary blood volume reductions. Also in the i.v. anesthetized animals the lung blood volume was relatively more reduced during a small bleeding than during a large one. A 12 % blood loss here caused only small volume changes in the splanchnic vascular bed, whereas a marked blood volume reduction occurred in this area after a 24 % blood loss. It appears that the pulmonary vascular bed of the rat is very sensitive to changes in total blood volume, and that it easily alters its capacitance in parallel with total blood volume changes.
The Metabolism of Liver Cholesterol in the Young Chick
Authors: Svanberg Olof , Svedjelund Anders
Published: December 2008

A mixture of 14C‐4‐cholesterol and 14C‐26‐cholesterol was injected into the invaginated yolks of newly hatched chicks which were then placed in metabolism chambers. By tracing the label in expired air, excreta (faeces+urine) and in their carcasses, the main pathways for the metabolism of the liver cholesterol could be estimated quantitatively. Over a period of 10 days about 26 % of the administered chclesterol was catabolized to bile acids, about 19 % was eliminated from the body as neutral steroids in the excreta and at the end of the 10th day about 55 % was retained in the carcasses. About 85 % of the bile acids synthesized was recovered in the excreta. As much as 45 % of the radioactivity derived from the 14C‐4 cholesterol in the excreta was associated with the neutral steroids, while 55 % was found in the bile acid fraction. The rate of bile acid biosynthesis estimated from the 14CO2‐production decreased from the fifth day after hatching. No estimation could be carried out during the days immediately following injection until isotopic equilibration had been reached. The faecal excretion of neutral steroids increased rapidly up to the fifth day, after which time it decreased. The body appears to treat part of the pre‐formed cholesterol from the yolk as a surplus which has to be eliminated. The specific activity of the cholesterol in the excreta collected on the 10th day was only about half of that of the intestinal content analyzed at the end of the same day.
Content of Blood and of Extravascular Water in Cat Lungs during Changes in Total Blood Volume
Authors: Bø P. Aarseth G.
Published: December 2008

A method has been developed which allows alterations in lung blood content and in extravascular lung water to be studied. The 2 upper lung lobes were removed separately from open‐chested cats. The first lobe was taken for control evaluations. The second one was removed when the circulatory situation had been changed. Labelled erythrocytes and plasma albumin had been injected beforehand. From the content of isotopes in the lung lobes, their blood volume could be calculated. Extravascular water was found by taking the difference between wet and dry weight of lung tissue, and correcting this difference for the blood content in that lobe. When total blood volume was reduced by a small bleeding, lung extravascular water content was reduced, and there was also a small reduction in lung blood volume. After a larger bleeding lung blood content was markedly reduced while the extravascular lung water content was then somewhat increased. Augmcntation of total blood volume by a blood transfusion led to an increase in lung blood volume, but to a decrease in extravascular lung water content.
Pulmonary Blood‐ and Extravascular Water Volumes during Prolonged Post‐Hemorrhagic Systemic Hypotension
Authors: Aarseth P. , Bø G.
Published: December 2008

In cats prolonged hemorrhagic hypotension had been shown to increase the pulmonary arterial pressure and vascular resistance. Pulmonary extravascular water volume and pulmonary blood volume have been evaluated early and late in such a period of post‐hemorrhagic hypotension. 51Cr‐labelled erythrocytes and 125I‐labelled albumin were injected intravascularly to animals with an opened chest and on positive pressure ventilation. One upper lung lobe was then suddenly clamped, removed and frozen. The lung lobe tissue and a simultaneously taken blood sample from a large vessel were measured for total w‐eight, dry weight and tracer content. The lobe's blood volume and extravascular water volume were then calculated per unit extravascular lung dry weight. A second lung lobe was removed and treated similarly at a later stage. 1 /2 h after the blood loss there was a marked reduction in lung blood volume and at the same time some increase in pulmonary extravascular water volume indicating constriction of postcapillary capacitance vessels. After 3 h of hypotension pulmonary extravascular water volume was found to be the same as before the hemorrhage although the pulmonary arterial pressure increased. This indicated that the increase in vascular resistance must predominantly be due to vasoconstriction at precapillary sites. The reduction in the lungs' blood volume remained at these late stages indicating that capacitance vessels were still constricted. When hyperinflations of the lungs were omitted in the experimental period, there was a tendency towards water accumulation in the lungs.
Single Glomerular Blood Flow as Measured with Carbonized 141‐Ce Labelled Microspheres
Authors: Källskoo Ö. , Ulfendahl H. R. , Wolgast M.
Published: December 2008

The blood flow to single cortical and juxtamedullary glomeruli was investigated in “normal” rats by means of a microsphere technique. Radioactively labelled microspheres were injected retrogradely into the ascending aorta and the number of spheres trapped in the glomeruli at different levels of the cortical parenchyma was determined by gamma‐spectrometry and related to the number collected from a catheter in the femoral artery. A uniform sphere size and no aggregates in the injected bolus were essential requirements for accurate blood flow determinations. The spheres were separated by sedimentation in water, which reduced the size range from a nominal value of 15±5 μ to 16.9±2.65 μ and gave no aggregates in the sedimented sample. The single glomerular perfusion was estimated to be 0.23 μl/min and 0.20 μl/min for cortical and juxtamedullary glomeruli, respectively. The difference was not significant (P > 0.5). The values correspond to estimations of total renal blood flow in the present and previous investigations.
The Functional Ultrastructure of the Blood‐Lymph Barrier. Computer Analysis of Data from Dog Heart‐Lymph Experiments using Theoretical Models.
Authors: Arturson G. , Groth T. , Grotte G.
Published: December 2008

A generalized two‐pore model including differences in permeability, surface area and pressure conditions along the capillary, was formulated and certain simplifications were tested with respect to their influence on the estimated parameters. A simplified version of the model was tested for compatibility and parameter confidence against a series of macromolecular sieving data obtained from Starling dog heart‐lung preparations. In these experiments heart‐lymph was collected during steady state conditions and the venous pressure was changed.

During “normal” conditions the blood lymph barrier of the dog heart‐lung preparations could be adequately described by an equivalent two‐pore membrane with small pores of radius 35–60 Å, and an additional set of larger pores of radius 120–160 Å, with the density of one large pore per 10,000 small pores. The mean transcapillary pressure difference was calculated to be less than 1 cm H2O.

During elevated venous pressure the effective surface area for fluid exchange was found to decrease to 1/2–1/3 of the normal value, due to a pronounced decrease in small pore radius. The concomitant increase in large pore radius caused an increased flow of fluid through the large pores. These results, in addition to the corresponding pressure perturbation data, have given some support to the pressure compensatory mechanisms suggested by Wiederhielm (1968).

The hypothesis that the transport of macromolecules takes place by way of cytopempsis was shown to be tenable if the ad hoc assumption was made that the vesicle size or density is pressure dependent.
In vitro Studies on the Uptake of Biogenic Amines by Rat Mast Cells
Authors: Heisler Seymour , Uvnäs Börje
Published: December 2008

Mast cells from rat peritoneal and thoracic cavities were isolated and incubated with biogenic amines (dopamine [DA], noradrenaline [NAa] and 5‐hydroxytryptamine [5‐HT]) or their precursor amino acids. Competition for uptake, saturation of mast cell amine stores (for 5‐HT and DA), and blockade of uptake by metabolic inhibitors indicate that simple passive diffusion does not suffice to explain the uptake by mast cells of the amines studied. The uptake of 5‐HT and DA appears to primarily involve active transport, whereas the uptake of Hi and NA may preferentially operate by facilitated diffusion.
Differential Effect of para‐Chlorophenylalanine on the Two Slow Wave Sleep Stages in the Cat
Authors: Ursin Reidun
Published: December 2008

The effect of an injection of 200 mg/kg para‐chlorophenylalanine (PCPA) on sleep was studied in 6 cats 48—72 h after the injection. Each cat was also given a control injection of the vehicle (BRIJ 35) 3 weeks before or after the experimental dose, in a balanced order. The main effect of PCPA was a reduction of the deep slow wave sleep (DSWS), with little effect upon the light slow wave sleep (LSWS) or rapid eye movement (REM) sleep. Both the number and the length of the DSWS episodes were reduced. For LSWS, only the length of the episodes was reduced. The number and the length of the REM sleep episodes were not changed. When the DSWS was reduced to 10 % or less of control values, there was a tendency to a decrease of LSWS and REM sleep also.
Cardiac Noradrenaline Turnover and Urinary Catecholamine Excretion in Trained and Untrained Rats during Rest and Exercise
Authors: ÖStman Ingegerd , Sjöstrand Nils O. , Swedin Göran
Published: December 2008

Rats were trained by daily swimming (1—2 h) during 15 weeks. The training caused a significant increase in heart weight. Cardiac noradrenaline (NA) and adrenal catecholamine (CA) contents were significantly increased in trained animals. When exposed to acute prolonged exercise the endogenous levels of cardiac NA decreased in untrained, but not in trained, rats. Resting cardiac NA turnover, as measured by rate of disappearance of exogenous3H‐NA, was slower in trained than in untrained rats (T1/2= 52 h and 20 h, respectively). The NA turnover increased during exercise, but still remained slower in trained rats. Figures were obtained indicating a significantly lower initial uptake of exogenous NA in the hearts of trained rats. Resting excretion of CA in the urine was not different in trained and untrained rats, while the increase seen after a period of exercise was much greater in the untrained animals. The results indicate that chronic physical training induces a functional adaptation of the sympathicoadrenal system leading to a better transmitter economy during exercise. The nature of this adaptation remains, however, unsettled.
In Vitro Work Load and Rat Heart Metabolism: III. Effect on ribosomal aggregation
Authors: Hjalmarson A. , Isaksson O.
Published: December 2008

In two preceding papers increased pressure load (afterload) was found to accelerate whole heart protein synthesis and amino acid transport in the perfused working rat heart (Hjalmarson and Isaksson 1972, Ahren et at. 1972). To further analyse this effect, sucrose gradient analysis of the postmitochondrial supernatant was performed to evaluate reactions involved in the ribosome cycle. When hearts were perfused in vitro under control conditions with buffer containing normal plasma levels of amino acids and with glucose as substrate, levels of polysomes decreased and levels of ribosomal subunits increased. These findings together with a decreased rate of protein synthesis indicated that a block in initiation of peptide chains had developed during perfusion. Perfusion of hearts with increased afterload increased the levels of polysomes and decreased the levels of ribosomal subunits and accelerated protein synthesis. The effects were obtained both when glucose and palmitate were used as substrate. Insulin further increased the levels of polysomes in pressure overloaded hearts and the ribosome profiles attained by overload in presence of insulin were identical to those obtained from unperfused hearts. Increased levels of polysomes and decreased levels of ribosomal subunits together with an increase in protein synthesis suggested that pressure overload stimulated reactions involved in the initiation of polypeptide chains. It is concluded that increased pressure load increases levels of initiation factors or changes the activity of enzymes regulating initiation processes in the ribosome cycle.
The Dynamic Properties of the Acoustic Middle Ear Reflex in Nonanesthetized Rabbits. Quantitative Aspects of a Polysynaptic Reflex System
Authors: Borg Erik
Published: December 2008

The open‐loop dynamic characteristics of the total acoustic middle ear muscle reflex (m. stapedius and m. tensor tympani) and of the isolated acoustic m. tensor tympani reflex were determined in unrestrained nonanesthetized rabbits. The frequency domain transfer functions of the reflexes were calculated on the basis of the responses to the onset and the decay of tone bursts independently. These functions had lowpass character and could be described by second‐order differential equations including a transport delay. The parameters of the equations were intensity dependent. At equal stimulus intensity the isolated m. tensor tympani reflex was slower than the total reflex. When the higher threshold of the m. tensor tympani was compensated for, the difference became small. The decay of the total reflex response was considerably slower than was the onset, decay of the isolated rn. tensor tympani reflex only slightly slower than its onset. The phase shift of the transfer functions for onset was greater than for decay possibly indicating a slip in the system. The closed‐loop properties of the total reflex and those of the isolated m. stapedius reflex were found to be closely similar. In addition, it was pointed out that the reflexes are slow in consideration to the small mass of the muscles, but that the dynamic properties seem to be well adapted to suit certain features of the afferent auditory system.
Depression of 3H‐Glucose Uptake into Rabbit Polymorphonuclear Leukocytes by Glucocorticoids in Concentrations Partly Saturating the Specific Glucocorticoid Uptake. Evidence for a Glucocorticoid Receptor
Authors: Simonsson Bengt
Published: December 2008

Rabbit polymorphonuclear leukocytes have a specific glucocorticoid uptake in vitro, half saturated by cortisol at a probably physiological concentration (about 3 × 10‐9 M). These cells in vitro accumulate 3H‐d‐glucose and 3H‐2‐deoxy‐d‐glucose, possibly by a common uptake step. Cortisol, dexamethasone, 9αF‐prednisolone, prednisolone, triamcinolone and triamcinolone acetonide, all in the low concentrations sufficient to partly saturate the specific glucocorticoid uptake, depress the uptake of 3H‐glucose by these cells. Corticosterone acted as a partial agonist. 11‐epicortisol, tetrahydrocortisone and progesterone, which have no glucocorticoid activity, had a very low activity on 3H‐d‐glucose uptake. For 11‐epicortisol and tetrahydrocortisone this corresponded to a low affinity to the specific glucocorticoid uptake process, while progesterone had a relatively high affinity. Progesterone in high concentrations was shown to block the depressing effect on 3H‐d‐glucose uptake by cortisol, probably by keeping it away from the specific glucocorticoid uptake process. Rabbit polymorphonuclear leukocytes thus seem to have a specific glucocorticoid receptor.
Plasma‐Kinins and Adrenergic Vasodilatation in the Submandibular Salivary Gland of the Cat
Authors: Gautvik K. M. , Kriz M. , Lund‐Larsen Kari
Published: December 2008

The submandibular salivary gland of the cat has been perfused in situ at constant volume inflow and in such a way that perfusion periods with kininogen‐containing and with kininogenfree perfusates alternated. The gland was stimulated with close arterial injections of nor‐adrenaline and the secretory and vascular responses recorded. Doses of noradrenaline which caused vasodilatation or no vascular effects when cat kininogen was present in the perfusate induced brisk vasoconstrictor responses in the same gland when a kininogen‐free perfusate was used. The vasoconstrictor responses could be gradually reduced and finally abolished as the gland was reloaded with cat kininogen. Glands which had undergone repeated stimulations with noradrenaline had a markedly lower content of kallikrein than had the contralateral, unstimulated organ. It is concluded that during adrenergic stimulation of the submandibular salivary gland, kallikrein is released into the interstitial space where it induces formation of plasmakinins. The plasma‐kinins formed cause vasodilatation, and they probably play an important role in the vasodilator response observed after a period with activation through the sympathetic nerves.
Choline Acetyltransferase in Salivary Glands after Surgical and Chemical Sympathectomy
Authors: Ekström Jörgen
Published: December 2008

An increase of the total activity of choline acetyltransferase occurs in the dog's parotid and in the submaxillary glands of the golden hamster and mouse after a surgical postganglionic sympathetic denervation. No such increase was found in the guinea‐pig's submaxillary gland; nor was it found in the rat's parotid and sublingual glands. A gradual enzyme increase was shown to begin after about 15 days in the rat's submaxillary gland. A chemical sympathectomy with 6‐hydroxydopamine had a similar effect as a surgical denervation; an enzyme increase was noticed in the rat's submaxillary but not in the sublingual gland. It is concluded that in the same species one type of gland may show the enzyme increase, while another type remains unchanged. A low enzyme concentration and a high density of adrenergic nerve fibres seem to favour the increase of the activity of choline acetyltransferase.
Repetitive Impulse Firing: Comparisons between Neurone Models Based on ‘Voltage Clamp Equations' and Spinal Motoneurones
Authors: Kernell Daniel , Sjöholm Hans
Published: December 2008

Repetitive impulse firing was elicited in neurone models by steady stimulating currents of abrupt onset. The neurone models were based on the Frankenhaeuser—Huxley equations (1964) for voltage clamp data from the amphibian peripheral nerve. A frequency‐current curve (‘f‐I curve’), initial adaptation, and minimum firing rate similar to those of cat spinal motoneurones were obtained in the Frankenhaeuser—Huxley model if it were provided with (i) a long‐lasting after‐hyperpolarization due to potassium permeability changes, and (ii) a decreased subthreshold sodium inactivation. For detailed comparisons to the repetitive impulse firing of spinal motoneurones, model versions were used in which the subthreshold sodium inactivation was very slight, and the passive membrane properties as well as the afterpotentials resembled those of spinal motoneurones. In their repetitive behaviour, these models were quantitatively similar to spinal motoneurones. In the motoneurone‐like model versions, initial adaptation was due to a kind of ‘summation’ of the potassium permeability changes underlying the after‐hyperpolarizations of consecutive spikes. The slope of the f‐I curve was markedly affected by modifications of the size or time course of the potassium permeability changes responsible for the after‐hyperpolarization.
Spectral Sensitivity of the Compound Eye in a Moth. Intra‐and Extracellular Recordings
Authors: Struwe Göran
Published: December 2008

The spectral sensitivity of the compound eye in a moth (Manduca sexta) was tested electrophysiologically by extracellular recordings in the wavelength region 310 to 650 nm, a) during dark‐adaptation, and b) during exposure to violet (408 nm) and red (680 nm) light. Sensitivity maxima were found at 370 to 390 nm, 450 to 470 nm, and 530 to 550 nm. During exposure to violet light a larger decrease in sensitivity was found for the maxima at 370 to 390 nm and 450 to 470 nm compared to that at 530 to 550 nm. During exposure to red light a larger decrease in sensitivity was found for the latter maximum. The results are interpreted as evidence for at least two photoreceptor types with different spectral sensitivity maxima. Intracellular recordings from single photoreceptors showed maxima in the same wavelength regions as those found extracellularly. The spectral sensitivities obtained were approximately similar. The homogeneity of the intracellular recordings is suggested to be due to interreceptor coupling.
Choline Acetyltransferase and Gholinesterase in the Pancreatic Duct of the Cat
Authors: Ekström Jörgen , Lenninger Sven
Published: December 2008

Choline aecetyltransferase has been demonstrated in the duct and parenchyma of the pancreatic: gland of the cat. Potentiation of the effect of acetylcholine on the contractility of ductal segments has been observed after eserinization, indicating the presence of cholinesterase in the duct. These findings are considered to indicate that the pancreatic duct of the cat is cholinergically innervated.
Role of Cyclic AMP and Ca++in Mechanical and Metabolic Events in Isometrically Contracting Vascular Smooth Muscle
Authors: Andersson Rolf
Published: December 2008

In bovine mesenteric artery catecholamines stimulated simultaneously adrenergic α‐and β‐receptors. The relaxation induced by a specific adrenergic β‐receptor stimulation was associated with an increased content of cyclic AMP, a phosphorylaseaactivation and a decrease of the content of ATP and creatinephosphate (CrP). No effect on the high energy phosphate compounds was present in the Ca++‐poor artery, but the effect on cyclic AMP and phosphorylase was still evident. Sotalol blocked all the actions induced by adrenergic β‐receptor stimulation. The contracting action induced by selective adrenergic α‐receptor stimulation was initially associated with a decrease of the cyclic AMP content, but when the tension was maximally developed, after 120 s, the cyclic AMP content was increased and the phosphodiesterase activity reduced. In Ca++‐poor artery a cyclic AMP decreasing effect was still present after 120 s and there was no reduction of the phosphodiesterase activity. The mechanical and metabolic effects induced by α‐receptor stimulation were blocked by dibenamine. Histamine, which increased the artery tension, significantly reduced the cyclic AMP content after 15 s, but after 5 min the level of cyclic AMP had increased and phosphorylaseawas activated. The mechanical and metabolic effects of histamine were blocked by promethazine, an antihistaminic drug. The role of cyclic AMP in relaxation and contraction of vascular smooth muscle is discussed.
EEG Synchronization and Sleep Induced by Stimulation of the Medial and Orbital Frontal Cortex in Gat
Authors: Alnæs E. , Kaada B. R. , Wester K.
Published: December 2008

Electrocortial synchronization, associated behaviourally with light sleep, was induced by low‐frequency stimulation of the subcallosal region and the orbital gyrus of the frontal lobe in unanesthetized cats. The effect was weaker than that obtained with basal forebrain stimulation. The above cortical areas have previously been shown to exert strong inhibitory influences on a variety of somatomotor and autonomic activities. High‐frequency stimulation of the same areas produces electrocortical desynchronization and behavioural arousal. It is suggested that the subcallosal and orbital portions of the frontal cortex give origin to.a descending system capable of modulating the excitatory state of sleep‐producing mechanisms in the brain stem or diencephalon.
Metabolism of Fracture Callus of Rat in vitro: I. Oxygen Consumption and Lactic Acid Production
Authors: Penttinen R.
Published: December 2008

Compared with the rat bone the oxygen uptake by the slices of callus is low during the proliferation of the cartilage in the callus and even lower during the active ossification. The production of lactate by the slices is equal to that of rat bone. These two parameters of the energy metabolism, expressed per whole callus, are maximal on the 9th day after the fracture, corresponding to the degeneration and calcification of the cartilage. Calculated on the weight basis, both parameters decline during the healing. The transition from cartilaginous to ossifying callus is characterized by a drop in the ratio of lactate produced to oxygen consumed. It is concluded that the energy metabolism in regenerating bone is mainly anaerobic thus resembling the granulation tissue.
Transcapillary Transport of D‐and L‐Glucose in Isolated Skeletal Muscle
Authors: Crone C.
Published: December 2008

The study was performed to clarify whether D‐glucose traverses muscle capillary walls faster than L‐glucose. The transcapillary transport of D‐glucose was slightly faster than that of L‐glucose in experiments at 37° C. The difference in transport rate persisted when the experiments were carried out at 4° C. This indicates that the faster transport of D‐glucose is not due to facilitated transport involving enzymatic steps. It is proposed that the ground matrix of the interendothelial cleft (and of the extravascular space) gives the D‐form of glucose a slight diffusional advantage over the L‐form. A pore effect cannot be completely ruled out.
An Attempt to Explain Nervous Transmitter Release as due to Nerve Impulse‐Induced Cation Exchange
Authors: Uvnäs Börje
Published: December 2008

An attempt is made to explain the storage and release of transmitters—particularly in the functional pool—at adrenergic and cholinergic nerve terminals as due to a cation exchange between amines bound to a sulphomucopolysaccharide‐protein complex in transmitter‐containing structures and inorganic ions in the neuro‐effector junctional gap. It is proposed that the exchange occurs at the nerve terminal membrane‐vesicle contact area during the period of nerve impulse‐induced depolarization and increased cation permeability (Fig. 2). The theory allows for a total or fractional release of the granule amine stores with or without a concomitant expulsion of the granule matrix. Such phenomena as reuptake, release by miniature end potentials, by amines and by drugs, fatigue etc. might also be explained on an ion exchange basis.
Circulatory Control via Vagal Afferents: III. Control of arterial blood pressure by afferents via the laryngeal communicans with special regard to the restitution after hemorrhage
Authors: Castenfors Jan , Knutsson Evert , Sjöstrand Torgny
Published: December 2008

The effect of afferent discharges via the laryngeal communicans on the control of the blood pressure has been studied in selected Sprague‐Dawley rats by cutting the inferior or/and superior laryngeal nerves at varying blood volumes. The subsequent changes can be divided into three phases: a brief excitatory phase, an intermediate and a late phase. The intermediate phase is characterized by an increase of heart rate and blood pressure, especially marked after hemorrhage. The late phase appears after a latency of about 20 min, is fully developed in one hour or more and consists, at ordinary or decreased blood volume, in a lowering and unbalance of the blood pressure. If the laryngeal pathway is excluded before or briefly after a blood loss of 30–40 % of the blood volume, the pressure is first restored to about 80 % of the initial level but then drops successively until the death of the animal in circulatory insufficiency. The effect of laryngeal deafferentation has been compared to the acute effect of hypophysectomia. The similarity of the delayed pressure regression at ordinary and decreased blood volume indicates that the laryngeal nerves act as a pathway for the stimulation of release of ADH vasopressin from the low pressure side.
Circulatory Control via Vagal Afferents: IV. Integration of the central control mechanisms in the circulatory‐adaptation to variations of blood volume
Authors: Castenfors Jan , Sjöstrand Torgny
Published: December 2008

The interrelations of receptor mechanisms localized to the central part of the cardiovascular system have been studied by alternative exclusion of afferent discharges via the laryngeal pathway, vagus trunk and sinus nerve in Sprague‐Dawley rats. An initial increase of arterial pressure followed by a lasting decrease, usually coincident with the appearance of pressure waves, was found in most animals on laryngeal deafferentation but in others on vagotomy. A preceding or subsequent exclusion of afferents via, respectively, the vagus trunk and laryngeal nerves exerted no or only small effects. The pressure response to occlusion of the common carotid arteries was decreased after blood infusions, also after hemorrhage to 60 mm Hg. On a further blood loss to a level of 25 mm Hg the response increased. Occlusion exclusively of the internal carotids provoked practically the same effect under these conditions. On laryngeal deafferentation and vagotomy, respectively, the pressure response increased. Deafferentation after blood infusion, especially combined with carotid occlusion and vagotomy, provoked forced respiration and in 3 of 6 animals signs of pulmonary edema, fatal in two. It was concluded that in hypervolemia the circulation is adapted wholly and in hypovolemia in part via afferents running in the laryngeal communicans and/or vagus trunk.
Degeneration Activity in the Rat Urinary Bladder
Authors: Elmér Mats
Published: December 2008

Periods of increased activity were found in the urinary bladder of the rat in situ 50–90 h after postganglionic parasympathetic denervation. The activity was not affected by hexamethoniuni, eserine produced an increase of the activity, and atropine and Hoechst 9980 totally abolished it. It is concluded that the activity is due to transmitter leaking from degenerating postganglionic nerve terminals and that the transmitter probably is acetylcholine.
Prostaglandins in Human Burn Blister Fluid
Authors: Arturson Gösta , Hamberg Mats , Jonsson Carl‐Evert
Published: December 2008

Acidic lipids with smooth muscle stimulating activity were isolated from human burn blister fluid. Analysis by silicic acid chromatography and thin‐layer chromatography indicated the presence of prostaglandin E and F compounds. Prostaglandin E2(about 1.9 ng/ml of blister fluid) was identified and quantitatively determined by gas‐liquid chromatography—mass spectrometry. No metabolic conversion of tritium‐labelled prostaglandin E1incubated with blister fluid was observed.
On the Regional Metabolism of Beef Heart Ventricles
Authors: Tota B.
Published: December 2008

The concentrations of some oligoelements (iron, copper, zinc) and electrolytes (calcium, magnesium, potassium) and the activity of the succinate‐cytochrome c reductase system were determined in various regions of the ventricles of beef heart. In the subepicardial layers of the ventricles and in the upper part of the septum a higher content of iron and copper and a greater succinate‐cytochrome c reductase activity were observed. These findings were consistent with a decreasing oxidative metabolic gradient both from the epicardium to the endocardium in the free ventricular walls and from the upper to the lower part of the septum. A higher content of potassium was demonstrated in the subendocardium of the ventricles. Significant differences in the concentrations of zinc, magnesium and potassium were found between the right and left papillary muscles.
A Study of the Effects of Some Chemically Welldefined Lissamine Greens on Tubular and Overall Renal Function in the Rat (with an evaluation of the validity of lissamine green transit time measurements in studies of tubular function)
Authors: Elmer Mogens , Leyssac Paul P.
Published: December 2008

Chemically different Lissamine greens were investigated for their immediate and late effects on renal functional parameters. The data indicate (1) that there was no consistent change in transit times (TT) in series of up to four repeated single injections with different LG completed within 8 min. (2) proximal and distal intratubular pressure responded to a single i.v. injection of LG with two distinct pressure increments, similar for all dyes tested. The first increase (prox.: 1–3 mm Hg; dist.: 1–2 mm Hg) coincided with a blood pressure response; the second increase (prox.: 1–2 mm Hg; dist.: 0.5–1.5 mm Hg) started when LG appeared in distal convolutions. The changes in flow velocity resulting from such pressure changes would not cause any significant error in the measured TT. (3) the late effects of LG were an increase in overall reabsorption capacity (predominatly in the loop of Henle) a parallel increase in glomerular filtration rate, and an increase in urine flow and osmotic excretion rate. Proximal reabsorption rate was unaffected. No difference in response was observed between different LG. Neither GFR nor urine flow changed significantly in control experiments in which a similar osmotic activity of mannitol was injected. It is concluded that TT measurements with LG may provide valid information on tubular function; but the late effects of LG would limit its use to a single measurement at the end of an experiment.
Oxygen Uptake, Muscle High‐Energy Phosphates, and Lactate in Exercise under Acute Hypoxic Conditions in Man
Authors: Knuttgen Howard G. , Saltin Bengt
Published: December 2008

The relationships among muscle metabolite concentration, exercise intensity, and oxygen utilization were studied under simulated altitude conditions (decompression chamber, 462 mm Hg b.p.). 5 male subjects exercised in 4 min bouts on a cycle ergometer at a wide range of exercise intensities (range 20–114% altitude max Vo2). Oxygen uptake was determined throughout exercise and recovery. Muscle biopsies (vastus lateralis) and fingertip blood samples were taken at rest and during recovery. Muscle ATP and creatine phosphate concentrations became reduced during exercise at all intensities. Little or no increase in lactate was observed below apprpx. 60% altitude max Vo2. The hypoxic condition caused a decreased acceleration from resting Vo2 and an increase in O2‐deficit at each absolute intensity as compared with normoxia. Close relationships were observed between level of high‐energy phosphate depletion and both O2‐deficit and fast component of O2‐debt not different from the same relationships under normoxic conditions. Virtually all differences in physiological response to identical exercise intensities at altitude as compared to normoxia were appropriately adjusted by expressing exercise intensity relative to the respective aerobic power capacities in the two conditions. Physiological responses to this type of exercise appear determined in great part by the availability of oxygen.
A Two‐Phased Change in Dynamic Lung Compliance during Hemorrhagic Hypotension
Authors: Bø Gunnar , Hauge Anton
Published: December 2008

Prolonged hemorrhagic hypotension and multiple trauma not involving the lungs can, in patients, induce respiratory failure with a fall in lung compliance and a concomitant increase in the work of breathing (Moore et al. 1969). However, animals experiments have revealed conflicting results concerning the magnitude and direction of change in lung compliance after a hemorrhage. We have studied the effects of 3 hr of hypovolemic systemic hypotension (femoral a. pressure: 50 to 60 mm Hg) on lung mechanics in open chest cats ventilated by positive pressure.

Mean dynamic lung compliance (CL) rose during the first 30 min post‐bleeding by 13 ± 5 per cent whereafter CL gradually fell to 26 ± 6 per cent below its initial value, in the third hr of observation. On the basis of our monitoring of vascular parameters and alveolar‐arterial PO2 differences we suggest that the early rise in CL is due to reduced pulmonary blood volume and vascular distending pressure, whereas the later fall in CL is caused by collapse and narrowing of peripheral airways. No signifiant changes in nonelastic (frictional) resistance could be detected during the 3 h observation period.
The Effects of Amytal and Inactin on Isosmotic Net Fluid Transport in the Rabbit Gall‐Bladder In Vitro
Authors: Christensen P. , ØStergaard Kristensen L. , Leyssac P. P.
Published: December 2008

The effects of the oxybarbiturate Amytal and the thiobarbiturate Inactin on isosmotic fluid absorption by the rabbit gall‐bladder in vitro sac‐preparation was studied. Both barbiturates inhibited net fluid transfer rate. The effect was dose‐dependent. Inactin was a more potent inhibitor than Amytal with effect from the serosal side at concentrations down to 1 × 10‐4M (i.e.below concentrations obtained in plasma of anesthetized rats); inhibition by Amytal unilaterally was not observed at concentrations below 1 × 10‐3M (a concentration above that of plasma of anesthetized rats). Amytal depressed oxygen consumption in parallel with net fluid transport rate, while Inactin was without any significant effect on oxygen consumption in spite of severe inhibition of net fluid transport rate. The inhibitory effect of Amytal applied bilaterally was reversible after exposure to the drug for more than 60 min. The effect of brief exposure (20 min) to Inactin bilaterally was reversible; after exposure for 60 min or more the effect was irreversible in recovery periods of up to 60 min duration. Both barbiturates accumulated in the gall‐bladder tissue with a concentration factor of about 1.5. After washing in barbiturate‐free Ringer solution (recovery periods) for 45–60 min, neither Amytal nor Inactin were detectable in the tissue. The sensitivity of the method allowed detection of 0.2 mM Inactin per kg wet weight,i.e.no more than 2% of the Inactin accumulated during the experimental period. The data suggested that the effects of the two barbiturates were additive.
Effects of Ionic Concentration on Permeability Properties of Nodal Membrane in Myelinated Nerve Fibres of Xenopus laevis. Potential Clamp Experiments
Authors: Brismar Tom
Published: December 2008

The specific sodium and potassium permeability mechanisms in the nodal membrane were analysed. The current to potential relations were measured with various external concentrations of NaC1, KC1 and CaC12. PNa and PK were calculated. The measurements showed that the permeability to potential curve was shifted along the potential axis and in the same direction for changes in the uni‐univalent salt concentration as well as for changes in [Ca]. The shift caused by changes in [Ca] was larger at low uni‐univalent salt concentrations and the shift caused by [K] and [Na] increased with decreased [Ca]. It was assumed that the membrane has negative charges fixed to its outside surface. The permeability shifts were approximately predicted by a charge density of‐5.5 μC μ cm‐2. A decrease in [Na], but not in [Ca] caused a decrease in PK. This behaviour was not predicted.
Muscle Metabolism and Enzyme Activities after Training in Boys 11–13 Years Old
Authors: Eriksson Bengt O. , Gollnick Philip D. , Saltin Bengt
Published: December 2008

The effect of training on the skeletal muscle metabolism of 11‐to 13‐year‐old boys was examined. In one experiment changes in blood lactate, and muscle lactate, CP, ATP, and glycogen were determined at rest and following exercise before and after 4 months of training. The concentrations of glycogen, CP and ATP at rest were higher (P<0.01) following training. Blood and muscle lactate were 23 and 56 % higher after maximal work following training. A greater reduction in muscle glycogen occurred during maximal work after training but the pattern for ATP and CP depletion was unchanged. In a second experiment boys trained by pedalling a bicycle ergometer an average of 30 min 3 times a week for 6 weeks. Biopsy samples of the vastus lateralis were examined for oxidative (succinate dehydrogenase) and anaerobic (phosphofructokinase) capacity before and after training. The fiber composition and relative oxidative capacity in the fibers was determined histochemically. Succinate dehydrogenase and phosphofructokinase activities increased 30 and 83 %, respectively, following training. Fiber distribution was unchanged by training but the oxidative capacity of both fiber types appeared to increase.