bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of Monosaccharide Permeability of Arterial Tissue and Intestinal Smooth Muscle; Effects of Insulin
Authors: Arnqvist Hans J.
Published: December 2008

The permeability of C14‐labelled D‐xylose and the accumulation of D‐glucose‐C14 were studied in rat and rabbit aorta and rabbit colon smooth muscle. C14‐labelled sucrose and sorbitol were used to estimate the extracellular space. In rabbit colon the distribution of sucrose‐C14 and sorbitol‐C14 reached an equilibrium after 30 min and were confined to about 40–50% of wet tissue weight. The initial distribution of D‐xylose‐C14 and D‐glucose‐C14 was the same as that of sucrose‐C14 and sorbitol‐C14 but reached no equilibrium after 30 min, instead there was a gradual increase which persisted for at least 150 min. The same results were obtained in rat and rabbit aorta. These findings indicate that D‐glucose and D‐xylose can penetrate the smooth muscle cell membrane, while sorbitol and sucrose are confined to the extracellular space. When rabbit colon was incubated for 60–180 min in D‐glucose‐C14 there was a continuous rise of tissue activity which exceeded a distribution in the extracellular space. The tissue concentration of unlabelled D‐glucose determined by an enzymatic method was constant during the same incubation times and corresponded to a distribution in the extracellular space. It seems probable therefore that the membrane permeability of D‐glucose is rate limiting for the metabolism of glucose in the smooth muscle cells.

Insulin (0.1 U/ml) increased moderately the accumulation of C14‐labelled D‐glucose in rat aorta and rabbit colon and the accumulation of D‐xylose‐C14 in rabbit colon.
The Action of Progesterone Derivatives and Other Steroids on the Sodium Transport of Isolated Frog Skin
Authors: Tomlinson R. W. S.
Published: December 2008

The ability of certain progesterone derivatives to inhibit the sodium transport of isolated frog skin has been compared relative to progesterone. Small changes in the steroid molecular structure reduces or abolishes its ability to cause inhibition. Cortisol produces similar effects to those already reported for aldosterone. Desoxycorticosterone exhibits the effects of both progesterone and aldosterone. 17B‐estradiol produced a stimulation and cortisone, pregnenolone, testoterone and estrone had no obvious effect.
On the Mechanism of Chlorpromazine‐Induced Histamine Release from Rat Mast Cells
Authors: Frisk‐Holmberg Marianne
Published: December 2008

On exposure to chlorpromazine in concentrations above 20 μM, histamine was released by rat mast cellsin vitro.Histamine release was unaffected by metabolic inhibitors, but was reduced by tetrodotoxin, elevated extracellular K+and Ca++concentrations. The cellular ratio of Na+and K+was changed, after treatment with chlorpromazine; sodium entered and potassium left the mast cells. It is concluded that chlorpromazine‐induced histamine release is secondary to permeability changes in the mast cell membranes and that Na+plays an important part in the release mechanism.
Adrenergic Innervation and Drug Responses of the Oval Sphincter in the Swimbladder of the God (Gadus morhua)1
Authors: Nilsson Stefan
Published: December 2008

The effects of drugs and of electrical stimulation of nerves on the circular and radial smooth muscles of the oval sphincter in the cod swimbladder have been studied. Opening of the oval seems to be caused by liberation of noradrenaline from vagal fibres in the muscularis mucosae. The noradrenaline relaxes the circular muscles by a beta effect, and contracts the radial muscles by an alpha effect. Acetylcholine contracts both circular and radial muscles, but no definite evidence for the existence of cholinergic fibres have been obtained. Closing of the oval may occur due to lack of adrenergic impulses. Adrenergic varicose nerve fibres have been observed running in both circular and radial muscle bundles, by use of a fluorescent histochemical method.
The Effect of Arterial Hypoxemia upon Acid‐Base Parameters in Arterial Blood and Cisternal Gerebrospinal Fluid of the Rat
Authors: MacMillan V. , Siesjö B. K.
Published: December 2008

The effects of hypoxemia on the acid‐base parameters of the arterial blood and CSF were studied in anesthetized constant ventilated rats. The results showed that there was a one to one relationship between the increase in the CSF lactate and the decrease in the CSF bicarbonate concentration over a wide range of arterial Po2 values. However, the decrease in the CSF pH at constant ventilation was much less than could be expected from the decrease in bicarbonate. This was due to a concomitant fall in the CSF CO2 tension, partly caused by a fall in the arterial CO2 tension and partly by a decrease in the Po2 difference between CSF and arterial blood.
Impulse Activity of the Isolated Spindle in Potassium‐Free Solution
Authors: Husmark I. , Ottoson D.
Published: December 2008

The effect of removal of potassium on the impulse activity of the frog muscle spindle was studied in isolated preparations. The spontaneous activity of the spindle increased over the first 30–40 min and then decreased and finally ceased. These changes were accompanied by alterations in configuration and time course of the action potential characterized by a decrease in amplitude and a lengthening of the impulse which developed into a heart‐like action potential. The sensitivity of the spindle to stretch decreased gradually with time and no conducted activity could usually be evoked by stretch 60–90 min after removal of potassium. Following return to normal Ringer the spontaneous activity and the response to stretch reappeared rapidly. The observed changes can partly be attributed to the effect of potassium removal on the conducted activity of the afferent axon and partly to the effect on the transducting function of the mechano‐sensitive endings.
The Effect of a Noradrenaline Liberator (4, alpha‐dimethyl‐meta‐tyramine) on Reflex Transmission in Spinal Gats
Authors: Fedina L. , Lundberg A. , Vyklický L.
Published: December 2008

In unanesthetized acute spinal cats an i.v. injection of 4, α‐dimethyl‐meta‐tyramine (H 77/77), which liberates noradrenaline (NA), depresses short‐latency transmission from the flexor reflex afferents (FRA) to motoneurones, ascending pathways and primary afferent terminals. The effect is similar to that produced by DOPA but the late flexor reflex evoked from the FRA after DOPA is not found after H 77/77. The effect by H 77/77 is reversed by the adrenergic α‐blockers phenoxybenzamine and chlorpromazine. H 77/77 has no effect in animals in which the stores of NA have been depleted by pretreatment with reserpine and a blocker of tyrosine hydroxylase. It is suggested that H 77/77 inhibits reflex transmission by transmitter liberation from noradrenergic terminals. H 77/77 also depresses short‐latency transmission from the FRA in chronic spinal cats after degeneration of the descending fibres. As a possible explanation it is suggested that the receptor sensitivity may have changed in the neurones deprived of NA terminals or that neighbouring glia cells may have taken over some of the functions of the NA terminals.
Inhibition of the Uptake of Biogenic Amines into Mast Cells by Tricyclic Psychoactive Drugs
Authors: Frisk‐Holmberg Marianne
Published: December 2008

The inhibitory effect of tricyclic neuroleptic and antidepressant drugs was investigated on the uptake of14C‐labelled 5‐hydroxytryptamine (5‐HT), dopamine (DA), noradrenaline (NA) and histamine (Hi) by isolated rat mast cells. All drugs inhibited the amine uptake but varied quantitatively and qualitatively in their blocking effects. Results showed that 5‐HT and NA uptake were competitively inhibited by both neuroleptics and antidepressants, whereas DA uptake only seemed competitively inhibited by neuroleptics.
Dipsogenic Effects of Intracarotid Infusions of Various Hyperosmolal Solutions
Authors: Olsson Kerstin
Published: December 2008

Thirst in response to intracarotid and intravenous infusions (1.5 ml/min) of various hypertonic, equi‐osmolal solutions was studied in the goat. Intracarotid infusions of 1 M NaCl and of 2 M fructose induced conspicuous cumulative drinking. The amount of water drunk during intracarotid infusions of 2 M urea and glycerol was only about a third of that consumed during the corresponding infusions of NaCl and fructose. During intracarotid infusions of 2 M galactose and glucose drinking was inconsistent. Of the intravenous infusions only hypertonic NaCl had a consistent dipsogenic effect. However, the amount of water consumed was considerably smaller and the latency time for drinking much longer than during the intracarotid infusions of NaCI. It is concluded that intracarotid infusions of hypertonic solutions act as considerably stronger thirst stimuli than corresponding intravenous infusions, and that the most pronounced dipsogenic effect is obtained by intracarotid infusions of those hypertonic solutions which also most effectively release antidiuretic hormone in the hydrated goat. The possibility is discussed that intracarotid infusions may stimulate the thirst mechanism indirectly via a rise in the Na+ concentration of the cerebrospinal fluid.
Sex Differences in the Catecholamine Output of Children
Authors: Johansson Gunn
Published: December 2008

Urinary excretion of catecholamines was studied in 240 normal, healthy children 12 years of age during a passive condition (film exposure) and an active condition (arithmetic test) at school. No sex differences in catecholamine excretion were found during the passive condition, whereas, during the work period, boys excreted significantly more adrenaline and noradrealine than girls. A comparison is made between catecholamine excretion levels of the children and adult subjects examined in other studies.
Increased Renal Excretion of Noradrenaline in Rats after Treatment with Prostaglandin Synthesis Inhibitor Indomethacin
Authors: Junstad Marianne , Wennmalm ÅKe
Published: December 2008

The renal excretion of noradrenaline (NA) during prolonged treatment with the prostaglandin synthesis inhibitor indomethacin (Indomée®) was studied in the rat. The excretion of NA was increased by about 50% during treatment with 0.5–2.0 mglkg b.w. of indomethacin, with a slight dose dependence. The results support the hypothesis, based on studies in isolated perfused organs, that thein uivorelease of NA from adrenergic nerve endings is limited by an endogenous, prostaglandin mediated braking system.
The Influence of Chlorpromazine on the Uptake of Biogenic Amines by Rat Mast Cells in vitro
Authors: Frisk‐Holmberg Marianne , Uvnäs Börje
Published: December 2008

Rat mast cells were incubated with14C‐5‐hydroxytryptamine (5‐HT),14C‐dopamine (DA),14C‐noradrenaline (NA) or14C‐histamine (Hi). The influence of amine concentrations, temperature and metabolic inhibitors indicate that carrier‐mediated transport mechanisms are involved in the uptake of the amines. Chlorpromazine (CPZ) in concentrations of 0.1–10 μM inhibited the uptake of 5‐HT, DA and NA competitively and reduced the uptake of Hi. Ca++ decreased the effects of CPZ. The results suggest that Ca++ may play an important part in the mechanism of action of CPZ.
Release of Acetylcholine in the Parotid Gland of the Dog during Stimulation of Postganglionic Nerves
Authors: Holmberg Jan
Published: December 2008

It has been found recently that the dog's parotid is supplied with postganglionic secretory fibres which travel not only in the auriculo‐temporal nerve but also outside this nerve in the adventitia of the internal maxillary artery. In the present experiments acetylcholine was found to appear in the perfusate from the gland when the auriculo‐temporal nerve was stimulated. When both this nerve and the fibres on the internal maxillary artery were excited, the yield of acetylcholine was doubled. It is concluded that the auriculo‐temporal nerve and the nerves on the internal maxillary artery contain cholinergic nerves in about equal amounts.
Effects of Malate and Oxaloacetate in Canine Subcutaneous Adipose Tissue
Authors: Fredholm Bertil B.
Published: December 2008

The effect of malate and oxaloacetate infusions was studied in the isolated canine subcutaneous adipose tissue. It was found that oxaloacetate (4–7 mM) reduced the venous lactate/pyruvate ratio, whereas malate (6–12 mM) increased it. During and following sympathetic nerve stimulation approximately equimolar amounts of glycerol and free fatty acids (FFA) were released. When oxaloacetate was infused the amount of FFA released increased, whereas the glycerol release was essentially unchanged. Malate, on the other hand, reduced the FFA release in spite of an essentially unchanged glycerol release. Both anions caused an increased uptake of glucose. The changes in re‐esterification induced were similar to that produced by the lactate/ pyruvate couple. The results are taken as circumstantial support for the concept that the degree of re‐esterification can be altered with the intracellular red‐ox state.
A Respirometer for Tissue Cultures of Liver
Authors: Sandström Bjorn
Published: December 2008

A simple differential respirometer equipment for experimental work with tissue cultures of liver is described. The respirometer works with small amounts of tissue (0.3–3 mg dry weight). The respiration values obtained indicate that the employed cultivation technique permits gas exchange at a rate adequate for normal liver also when the working gas phase consists of ordinary air.
Reactions within Consecutive Vascular Sections of the Small Intestine of the Cat during Prolonged Hypotension
Authors: Haglund Ulf , Lundgren Ove
Published: December 2008

A plethysmography technique was utilized to investigate the reactions within consecutive vascular sections of the small intestine of the cat during and after a 2–3 h local arterial hypotension at approximately 55 or 30 mm Hg produced by graded arterial occlusion. The sympathetic nerves to the intestine were cut. The resistance vessels were dilated during hypotension, the dilatation being more pronounced the lower the perfusion pressure. In the early phase of hypotension this autoregulation of intestinal blood flow was probably mainly “myogenic” while it was predominantly “metabolic” in the late part of hypotension. When releasing the arterial occlusion, blood flow returned to control after a 55 mm Hg hypotension, while a marked prolonged vasodilatation was observed after the 30 mm Hg hypotension. The capillary filtration coefficient was not changed from control during a hypotension at 55 mm Hg while it was enhanced at 30 mm Hg. Mean capillary hydrostatic pressure seemed to increase in the latter half of most experiments performed at this level. An additional, transient augmentation of capillary pressure seemed to occur after the hypotension. Upon releasing the arterial clamp after a 30 mm Hg hypotension the whole cardiovascular system seemed to derange progressively to judge by a decline of arterial blood pressure.
Uptake of 3H‐Atropine in the Pancreatic Islets and the Parafollicular Cells of the Thyroid in Mice Shown by Microautoradiography
Authors: Slanina Premysl , Tjälve Hans
Published: December 2008

Male albino mice were injected with 3H‐atropine and killed 5 min, 30 min and 2 h after the injection. The distribution of radioactivity in the pancreas and the thyroid was then studied with a microautoradiographic technique for isotopes in water soluble form. In the pancreas the highest radioactivity was found in the pancreatic islets. In the thyroid the radioactivity was most strongly accumulated in cells with a distribution corresponding to the parafollicular cells. A method for a combination of monoamine fluorescence with microautoradiography was also used to show that the cells of the pancreatic islets and the parafollicular cells of the thyroid, which are capable of monoamine accumulation after monoamine‐precursor injection, also are capable to accumulate atropine.
The Oxygen Supply to the Retina, I. Effects of Changes in Intraocular and Arterial Blood Pressures, and in Arterial PO2 and Pco2 on the Oxygen Tension in the Vitreous Body of the Cat
Authors: Alm Albert , Bill Anders
Published: December 2008

The Po2 in the vitreous body close to the retina, PvrO2, was determined continuously with an O2 electrode. In cats with a mean arterial blood pressure of 176±7 cm H2O, a PaO2 of 98±2 mm Hg, a PaC02 of 27.0±1–2 mm Hg and a pH of 7.43±0.16 units the mean PVr02 was 18.9±1.5 mm Hg. Stepwise increments in the eye pressure had no effect on PVrO2 at perfusion pressures above 50–100 cm H2O. At lower perfusion pressures PvrO2 decreased. Changes in perfusion pressure caused by hemorrhage and retransfusion gave similar results. At low Paco2 levels PvrO2 decreased; at high PaCo2 levels values of 40–60 mm Hg were observed. Reductions in Pao2 decreased Pvro2, increments gave either no change or a rise in Pvr02‐ Hypercapnia combined with high Pao2 in several cases resulted in PVr02 values between 100 and 150 mm Hg. The results indicate that the blood flow through the retina is very efficiently autoregulated, that oxygen tends to induce vasoconstriction in the retinal blood vessels, that hypocapnia gives vasoconstriction and hypercapnia marked vasodilatation.
Storage of 5‐Hydroxytryptamine in Rat Mast Cells. Evidence for an Ionic Binding to Carboxyl Groups in a Granule Heparin‐Protein Complex
Authors: Bergendorff Anders , Uvnas Borje
Published: December 2008

Bergendorff, A. and B. Uvnas.Storage of 5‐hydroxytryptamine in rat mast cells. Evidence for an ionic binding to carboxyl groups in a granule heparin‐protein complex.Acta physiol. scand. 1972.84.320–331.

Basophil granules were isolated from rat peritoneal and thoracic mast cells. The granules were depleted of their endogenous Hi and 5‐HT and the amine storing properties of these depleted granules were studied. The influence of pH, the uptake capacity, the releasing action of sodium ions and the competitive uptake of Hi and 5‐HT by the granule stores all support the hypothesis that the granule stores have the properties of a weak cation exchange resin. It appears that 5‐HT release, as we previously showed for Hi‐release, is due to a cation exchange occurring on mast cell degranulation, when the amine‐containing granules become exposed to cations of the extracellular milieu.
The Influence of the Crowding Phenomenon on the Oxygen Consumption of Blood Cells as Determined by the Cartesian Diver Technique
Authors: Talstad Ingebrigt
Published: December 2008

Talstad, I. The influence of the crowding phenomenon on the oxygen consumption of blood cells as determined by the Cartesian diver technique. Acta physiol. scand. 1972. 84. 332–337.

The tendency of decrease in oxygen (O2)‐consumption per cell with increase in cell concentration during measurements (crowding phenomenon) was studied with the Cartesian diver technique. The theoretical linear relationship between O2‐consumption and the number of ceils was found for polymorphonuclear leukocytes (PMN), lymphocytes and platelets with the standard divers, the capillar) type of divers giving the same results as standard divers. However, marked crowding phenomenon occurred at high numbers of PMN, lymphocytes or platelets per diver. An explanation for the crowding phenomenon is probably deficient O2‐equilibration during measurements and not a peculiar phenomenon of PMN or lymphocytes as has so far been suggested.
The Glomerular Filterability of Inulin and of Different Molecular Weight Preparations of Polyethylene Glycol in the Rabbit
Authors: Jorgensen K. E. , Møller J. V. , Sheikh M. I.
Published: December 2008

Jorgensen, K. E., J. V. Møllerand M. I. Sheikh. The glomerular filterability of inulin and of different molecular weight preparations of polyethylene glycol in the rabbit. Acta physiol. scand. 1972. 84. 408–414.

It has been claimed on the basis of clearance experiments that inulin is incompletely filterable through the glomerular membrane of the rat kidney (Berglund 1964, 1965). In the present study the renal excretion in the rabbit of inulin and different preparations of polyethylene glycol has been compared during constant infusion of these substances. Identical clearance values were obtained for inulin and polyethylene glycol, having molecular weights of 1500 (PEG–1500) and 4000 (PEG–4000). The ratio of the clearances between polyethylene glycol of a molecular weight of 6000 (PEG–6000) and inulin was smaller than unity (0.89±0.03). Gel filtration analysis of plasma and urine samples indicated unrestricted filtration of inulin through the glomerular membrane of this species. Furthermore, gel filtration and ultrafiltration experiments indicated that the molecular size of inulin and PEG–1500 is similar, while the molecular dimensions of PEG–6000 exceed that of the most high molecular weight fractions of inulin. It is concluded that the clearance of inulin, PEG–1500, and PEG–4000 may be used as a measure of the glomerular filtration rate in the rabbit, whereas the glomerular filtration of PEG–6000 is restricted to some extent. The incomplete filterability of PEG–6000 is attributed to the relatively larger molecular size.
Convergence of Large Muscle Spindle (Ia) Afferents at Interneuronal Level in the Reciprocal Ia Inhibitory Pathway to Motoneurones
Authors: Hultborn H. , Udo M.
Published: December 2008

It has earlier been established that in a number of motor nuclei la inhibition can be evoked from several muscles. It has now been investigated if this convergence takes place already at the interneuronal level or if the la inhibition from the different muscles is exerted through separate interneuronal pools which then converge at motoneuronal level. With intracellular recording from motoneurones and utilizing the technique of spatial facilitation it has been demonstrated that when activity in la afferents from several muscles can evoke inhibition in a given motoneurone a convergence of these la afferents does occur onto common interneurones.
Cerebrospinal Fluid Clearance of Choline and Some Other Amines
Authors: Aquilonius Sten‐Magnus , Winbladh Birger
Published: December 2008

The elimination from CSF of the quaternary ammonium compounds choline, methylatropine and decamethonium and the tertiary amine atropine has been investigated by ventriculo‐cisternal perfusion in anesthetized dogs and rabbits. The elimination of the amines from the perfusate was partly concentration dependent. Further, in the rabbit experiments they decreased the elimination of each other. In the dog 63 per cent of the infused choline was eliminated between the lateral ventricle and cisterna magna at an infusate concentration of 5·10‐‐6M and a rate of 150 μl/min. The corresponding figure for the rabbit was 78 per cent at 30 μl/min. Brain drug concentrations after the experiments revealed that diffusion into the brain contributed to the elimination only to a minor extent. Results were compared to invitrostudies on choroid plexa. A correlation was found between the rate of removal from perfusate for the quaternary drugs and their uptake characteristicsin vitro. The conclusion was drawn that the investigated amines are eliminated from CSF partly by a carrier mediated process. One important site of this process is probably the choroid plexus.
Utilization of Yolk Cholesterol in the Developing Chick Embryo
Authors: Jain Shashi Kumar , Lindahl Per Eric , Svanberg Olof
Published: December 2008

14C‐4‐cholesterol was injected into fertilized hens' eggs after different incubation times. The embryos were removed after various times and subjected to auto radiographic examination. By tracing the label at subsequent stages of development, the time sequence for the utilization of the pre‐formed yolk cholesterol has been determined. Up to the 8th day of incubation the cholesterol from the yolk was homogeneously distributed in the embryo, with a slightly higher concentration in the peripheral parts of the spinal cord and in the some areas of the brain. Two days later a slight elevation of the liver 14C‐cholesterol concentration occurred, followed by a rapid increase after the 15th day. Bile was first secreted on the 11th‐12th day. The incorporation of 14C‐cholesterol into the central nervous system was partly restricted after the 8th day. From the 15th day hardly any labelled cholesterol was incorporated in the brain and spinal cord; a specific blood‐brain barrier had been established. The peripheral nerves, however, were intensively labelled by the 19th day. By this time the adrenals and the gonads contained more labelled cholesterol than other tissues.
Increased Activity in Left Ventricular Receptors during Hemorrhage or Occlusion of Caval Veins in the Cat. ‐ A Possible Cause of the Vaso‐vagal Reaction
Authors: ÖBerg Bengt , Thorén Peter
Published: December 2008

Impulse activity in vagal afferent fibres and changes in heart rate were simultaneously recorded during rapid hemorrhage or blood pooling in cats in order to elucidate whether the sudden reflex bradycardia, sometimes evoked with the mentioned interventions, was correlated to an increased activity in any type of heart receptors. The results show that the slowing of the heart, resulting from an emptying of the central blood reservoirs was correlated to, and preceded by, an increased activity in receptors located in the left ventricle and signalling in non‐medullated afferents. The receptors were found to be activated also by obstructions of the ascending aorta and mechanical stimulation of the heart, and therefore seem to operate as mechanorecepton, stimulated by a “distortion” of the myocardium. ‐ It is conceivable that with rapid bleeding or pooling of blood, the receptors are excited by an improper squeezing of the myocardium when the ventricles contract vigorously around an almost empty chamber, and then induce a reflex bradycardia. This reflex mechanism, resembling the so‐called vaso‐vagal syncope reaction in man, may therefore serve as a protective system causing a break on the heart and allowing for an improved diastolic filling in situations when venous return is critically reduced.
The Influence of Deep Barbiturate Anesthesia upon the Regulation of Extra‐ and Intracellular pH in the Rat Brain during Hypercapnia
Authors: Messeter Kenneth , Pontén Urban , Siesjö Bo K.
Published: December 2008

In order to study the influence of deep barbiturate anesthesia upon the regulation of extra‐ and intracellular pH in the brain, hypercapnia was induced in rats anesthetized for maximally three hrs with either 200–250 mg/kg of phenobarbital, or with 0.6 % halothane. There were no differences in the regulation of the CSF pH between the groups studied. However, both at 15 min at and 3 h the phenobarbital anesthesia was associated with a less efficient regulation of the intracellular pH'. At 15 min the regulation observed came close to that expected on the basis of pure physicochemical buffering. It is concluded that deep phenobarbital anesthesia, probably due to its effect on metabolism, can interfere with the mechanisms which regulate intracellular pH' during hypercapnia.
Hemodynamic Responses of Relaxed, β‐Blocked and Shivering Dogs during Hypothermia
Authors: Halkola Lauri , Koivikko Antti , Länsimies Esko
Published: December 2008

7 dogs were anesthetized only, ten dogs anesthetized and relaxed. Additionaly three dogs were anesthetized, relaxed and β‐blocked. All dogs were ventilated by oxygen. Hypothermia was produced by ice‐water immersion. The oxygen consumption decreased in all but the shivering group. Initially, the cardiac output increased in the shivering group, decreased in the β‐blocked group but an unexpected slight increase was observed in the relaxed group. The reason for this observation is being discussed.
Dehydration‐Induced Reductions in Total Blood Volume and in Pulmonary Blood Volume in Rats
Authors: Aarseth P. , Klug D.
Published: December 2008

Groups of rats were exposed to water deprivation and/or food deprivation for 24 h periods. The degree of dehydration obtained was evaluated by weight examinations of the differently treated rats. The plasma and erythrocyte volumes were estimated by the use of i.v. injected isotopes. It was found that on water deprivation the intravascular fluid compartment was reduced relatively more than the total body water content. The blood content in the lungs was estimated from the organ content of isotopes after the rats had been rapidly frozen in liquid nitrogen. When dehydration had caused an 8 % reduction in the total blood volume, the pulmonary blood volume was found to be reduced by 30 %. The pulmonary vascular compartment thus appears to function as an important blood depot in this connection.
Effects of Alterations in Calcium Concentrations on Secretion and Protein Synthesis in Cat Submandibular Salivary Gland
Authors: Gautvik K. M. , Kriz M. , Lund‐Larsen Kari
Published: December 2008

The effects of low Ca++concentrations on secretory responses induced by injections of nor‐adrenaline to the perfused cat submandibular salivary gland have been investigated. Particular attention has been paid to the release of kininogenase (a kinin‐forming enzyme). Kininogenase activity was measured in saliva, in effluent perfusate and in gland homogenate. When perfusion media containing no added Ca++was used, a reduced amount of saliva with a normal concentration of kininogenase was secreted. Additional reduction to near zero of [Ca++] in perfusion fluid by the use of EGTA blocked saliva secretion. However, a fall in remaining kininogenase activity was still observed in homogenates from activated glands, although less marked than in the activated control glands. Low perfusate [Ca++] also reduced the incorporation of14C‐L‐Leucine into proteins of non‐activated glands by an average of 52 per cent. It is concluded that the secretion of water and ions is blocked and that the release, and probably also the synthesis, of glandular kininogenase is reduced under conditions of low concentrations of Ca++in the perfusate.
Effect of Training on Esterified Fatty Acids and Carnitine in Muscle and on Lipolysis in Adipose Tissue in Vitro
Authors: Fröberg Sven O. , ÖStman Ingegerd , Sjöstrand Nils O.
Published: December 2008

The concentration of triglycerides, phospholipids and carnitine was determined in red and white parts of the gastrocnemius muscle from rats with and without a period of training by running. Also the rate of lipolysis in adipose tissue was determined with and without stimulation in vitro. The concentration of triglycerides was reduced in the red and white muscle tissue but positively correlated to each other in white muscle tissue. This suggests that the white muscle tissue. Correlation analysis revealed no direct relationship between the spontaneous or stimulated rate of lipolysis in vitro and the triglyceride concentration in either type of muscle tissue. This suggests that the level of muscle triglycerides was influenced or deter‐mined by other factors than the rate of mobilization of fatty acids from the adipose tissue per se. The concentrations of carnitine and triglycerides were negatively correlated in red muscle tissue but positively correlated to each other in white muscle tissue. This suggests that the metabolic role of carnitine with regard to triglyceride metabolism differed between the two muscle types. The possibility was discussed that the capacity of the intracellular carnitine transport system for fatty acids into mitochondria of red muscle tissue increased in the course of physical training as part of an adaptation towards enhanced oxidative metabolism.
Regulation of Middle Ear Sound Transmission in the Nonanesthetized Rabbit
Authors: Borg Erik
Published: December 2008

The regulation of sound transmission through the middle ear of nonanesthetized rabbits was quantitatively investigated by comparing the excitation of the cochlea before and after surgical inactivation of m. stapedius and/or m. tensor tympani in the stimulated ear. The crossed middle ear reflex was used as a measure of the excitation of the cochlea to stimulation with pure tones in the range from 0.5 to 8.0 kHz at intensities up to 125 dB SPL. Sounds through this frequency range were attenuated above a level of 90 to 100 dB SPL. Low frequency tones (0.5 kHz) were attenuated by all levels of activity in the m. stapedius and m. tensor tympani. High frequencies were attenuated only by m. stapedius activity at high intensity levels above reflex threshold (20–30 dB). The m. tensor tympani had no influence on high frequencies, above 2.0 kHz. Improved sound transmission due to reflex activity was not regularly found. The efficiency of the regulation was regarded as high: a 1.0 dB increase in sound level in the ear canal gave only a 0.3 dB increase in the excitation of the cochlea (i.e. the regulating efficiency of the closed‐loop system was 0.7 dB attenuation per 1.0 dB increase in stimulus sound intensity). The regulating efficiency of the open‐loop system was about 2 dB/dB. The open‐loop gain was estimated to 4 during steady‐state. The oscillations in the middle ear reflex response were found to be generated in the m. stapedius feed‐back loop regulating the sound transmission through the middle ear. It was concluded that the function of the acoustic middle ear reflexes can be described as extending the dynamic range of the cochlea and adaptation and it may also be compared with the effect of lateral inhibition.
Production and Removal of Lactate during Exercise in Man
Authors: Hermansen Lars , Stensvold Inger
Published: December 2008

Blood lactate concentration (LA) was measured in 4 female and 3 male well‐trained subjects before and during 30 min of continuous treadmill running at 4 different speeds, demanding about 30, 60, 70 and 80% of the individuals' maximal oxygen uptake (Vo2 max). The same subjects also performed in another series of experiments where maximal intermittent exercise preceded 30 min of running at the same 4 speeds, or resting in a chair. During continuous running, starting from resting conditions, the blood LA increased only slightly up to a critical Ievel (i.e. 60—80%) of Vo2‐max. From then on, a pronounced lactate production may occur. During the maximal intermittent exercise, blood LA increased to 130—220 mg/100 ml. In the recovery period, i.e. continuous running at the same 4 speeds, or resting in a chair, blood LA decreased towards resting values. The lactate removal rate was calculated from the rectilinear part of the curves describing the changes in LA with time, and expressed as mg/100 ml X min. The lactate removal rate was higher during exercise than during rest, and increased with increasing work load up to the same critical level (i.e. 60—80% of Vo2 max), beyond which a reduction was observed. The highest removal rate was 8 mg lactate/100 ml x min at 63% of Vo2 max (average values). These results indicate that human skeletal muscle possesses a pronounced capacity to oxidize lactate. Therefore, a production of lactate is possible even with no increase in the blood LA. These results also indicate that the skeletal muscle, rather than the liver, may be regarded as the main site for lactate removal during exercise.
Low Flow States in the Microvessels of Skeletal Muscle in Cat
Authors: Eriksson Elof , Lisander Björn
Published: December 2008

With the tenuissimus muscle exposed for vital microscopy, the effects on macro‐ and micro‐circulation of aortic compression and of arterial bleeding were studied in cats anesthetized with chloralose. In the first case, arterial pressure in the hindlimbs was kept at 50 mm Hg for 2 ½ h and in the latter, the animal was rapidly bled with 40% of its total volume, and then observed for up to 4 h. — During aortic compression arterioles of 25 μm internal diameter increased their dimensions with about 40% and arteries of 70 μm with about 15%. The diameters of the venules showed a slight decrease. Linear flow rates in the capillaries decreased but there was an even distribution of the blood flow. No formation of thrombi was seen. — At arterial bleeding all the vessels first reduced their diameters during 10—20 min. Then arterioles of 25 μm diameter dilated, while the diameters of the other vessels remained reduced. In average the cats survived for 2 ½ h. Within a few minutes after the bleeding there was an adhesion of white cells to the venular walls and in later stages aggregates of red cells, platelets and white cells started to occlude most venules and capillaries leading to extensive “functional shunting” at the capillary level.
Coding of Amplitude and Frequency Modulated Sounds in the Cochlear Nucleus of the Rat
Authors: Møller Aage R.
Published: December 2008

The responses of single units in the cochlear nucleus of the rat to sinusoidally amplitude‐ and frequency‐modulated tones and amplitude‐modulated broadband noise were studied. The distribution of discharges within a cycle of modulation was determined from cycle histograms locked to the modulation wave. In response to amplitude‐modulated tones and broadband noise, all units investigated showed a peak in the degree of modulation of the spike frequency within the modulation frequency range from 50 to 200 Hz. In many units the relationship between the degree of modulation of the stimulus sound and of the modulation of the resulting spike train was almost unchanged over a wide range of sound intensities. In other units, enhancement of modulation within a certain range of modulation frequency became more pronounced when the sound intensity was increased. This was mainly due to a suppression of modulation at lower modulation frequencies. The shape of the histograms was nearly sinusoidal even at modulation depths which resulted in nearly 100% modulation of the neural discharge frequency. The amount of modulation of the discharge frequency in response to frequency‐modulated tones was dependent on the frequency of the tone in relation to the CF of the unit.
Lipid Biosynthesis from DL (2‐14C) Mevalonic Acid in Intact Mice and Rabbits
Authors: Edgren Bo , Hellström Kjell
Published: December 2008

DL‐mevalonate‐2‐14C was administered parenterally to 2 rabbits and 5 groups of mice. In the rabbits the amount of labelled material recovered in the non‐saponifiable lipids of the kidneys exceeded that of the liver. Most of the renal radioactivity was found in the squalene, lanosterol and methostenol fractions whereas the major part of the labelled material in the liver was present as radioactive cholesterol. The distribution of radioactivity within the kidney and the liver in the mice varied with the size of the administered dose. The smaller the dose, the larger the proportion of label recovered in the kidneys. In all experiments most of the radioactivity of the liver was transformed to cholesterol. The conversion of squalene to cholesterol proceeded more slowly in the kidneys and 30 min after the administration of the mevalonate substantial amounts of radioactivity was recovered as labelled squalene and lanosterol. The importance of circulating mevalonate as substrate in the cholesterol synthesis of the kidney will be discussed.
Functional Dependence of the Ciliary Epithelium ATPase Activity and Intraocular Pressure on the Autonomic Nervous System
Authors: Härkönen Matti , Palkama Arto , Uusitalo Risto
Published: December 2008

Regulation of intraocular pressure by autonomic nerves of the eye was studied using three types of denervation: sympathectomy, ciliarectomy or coagulation of the parasympathetic nerves (around the optic nerve). Intraocular pressure, inflow and outflow were registered manometrically using a constant pressure infusion technique. ATPase activities in the ciliary processes were demonstrated histochemically and assayed fluorometrically. Special attention was paid to the biochemical characteristics of the ciliary body NaK‐ATPase activity. A kinetic fluorometric method for NaK‐ATPase was developed. Intraocular pressure decreased after ciliarectomy simultaneously with a decrease in inflow of the aqueous humour. Ciliary body‐iris NaK‐ATPase activity also decreased. The changes in the ocular fluid dynamics after coagulation of the parasympathetic nerves tended to be the same. Intraocular pressure decreased as well as NaK‐ATPase activity. Sympathectomy, however, did not change ocular fluid dynamics or NaK‐ATPase activity. The ciliary body‐iris NaK‐ATPase activity seemed to have the characteristics of the transport enzyme found in other organs. It was activated by Na+, K+ Mg++ could be inhibited by ouabain. Activity was optimum when the Mg++/ATP ratio was about 1 and the optimal pH both for Mg‐ and NaK‐ ATPase was 8.1. The results give further support to the theory that intraocular pressure is under nervous control. This regulation is mediated by decreased inflow, which in turn is reflected by a lowered NaK‐ATPase activity in the ciliary processes.
Response to Submaximal and Maximal Exercise at Different Levels of Carboxyhemoglobin
Authors: Ekblom Björn , Huot Roger
Published: December 2008

Five subjects performed submaximal and maximal bicycle and maximal treadmill exercise in normalcy and after carbon monoxide inhalation, giving different levels of carboxyhemoglobin (COHb) in the blood. During maximal treadmill exercise work time on a fixed work load and maximal oxygen uptake were decreased with increasing level of COHb (r = 0.79 and r = 0.85, respectively). Peak blood lactate concentration and pulmonary ventilation were unchanged. Highest measured heart rate was lower in parallell with the increased COHb level compared to control studies. During submaximal work heart rate was increased and oxygen uptake was unchanged at the various levels of COHb. At low submaximal work loads blood lactate concentrations and oxygen deficit was unchanged but increased as work load and COHb‐level increased.
Augmented Noradrenaline Release Following Nerve Stimulation after Inhibition of Prostaglandin Synthesis with Indomethacin
Authors: Pham‐Huu‐Chanh  , Junstad Marianne , Wennmalm ÅKe
Published: December 2008

The effect of inhibition of prostaglandin synthesis on the release of noradrenaline induced by sympathetic nerve stimulation was studied in the isolated perfused rabbit heart. It was found that indomethacin (Indomeé®, Merck, Sharp and Dohme), a drug known to inhibit prostaglandin synthesis, decreased the outflow of prostaglandins normally induced by nerve stimulation. Simultaneously the outflow of noradrenaline in response to nerve stimulation was augmented. Since indomethacin neither caused any release of noradrenaline heart in the absence of nerve stimulation, nor affected the uptake of exogenous noradrenaline, it is concluded, that the increased noradrenaline release reflects disinhibition of a feed‐back mechanism, using endogenously formed prostaglandins for limitation of noradrenaline release.
The Effect of Hypercapnic Acidosis upon the Energy Metabolism of the Brain in Arterial Hypotension Caused by Bleeding
Authors: Eklöf Bo , MacMillan Vernon , Siesjö Bo K.
Published: December 2008

The effect of hypercapnia upon the sensitivity of the cerebral energy metabolism to low perfusion pressures was studied by decreasing the mean arterial blood pressure to 60 and 45 mm Hg, respectively, in rats maintained at arterial CO2 tension of 60–65 mm Hg. The hypercapnia gave rise to a moderate extra‐and intracellular acidosis. The cerebral venous Pco2 rose and remained above 50 mm Hg even in the hypotensive groups. In spite of this venous hyperoxia a reduction of the mean arterial blood pressure to 60 mm Hg gave rise to slight but consistant changes in the tissue concentrations of adenine nucleotides. At a pressure of 45 mm Hg there was a major derangement of the energy state of the tissue in 4 out of 6 animals. It is concluded that hypercapnic acidosis adversely affects the cerebral energy metabolism in hypotensive states, probably by inducing a flow pattern which leads to regional ischemia.
Nonlinear Dynamic Properties of a Somatomotor Reflex System. A Model Study
Authors: Borg Erik
Published: December 2008

The time course of polysynaptic reflex responses is known to exhibit two prominent non‐linearities, one dependent on the amplitude of the stimulus and the other dependent on the direction of change of the stimulus. Both nonlinearities were demonstrated in the open‐loop responses of the acoustic middle ear reflex and simulated in a piecewise linear model. Their significance for stability of the closed‐loop feed‐back system was investigated. In this model the source of nonlinearity was a pool of “reflex units” with various thresholds and time constants. The mode! responses were studied in the time domain and the frequency domain. The amplitude dependent nonlinearity could be simulated when low threshold reflex units were made slow and tonic and high threshold units fast and tonic or when some of the high threshold units were phasic. A decrease in transport delay at increased input step amplitude was seen under these conditions but also when all units mere made equal. Both types of nonlinearities were found to improve the stability of the model system without decreasing its bandwidth (a measure of the speed of action). The nonlinearities were suggested to be important in systems with high values of transport delay.
Reflex Bradycardia Elicited from Left Ventricular Receptors during Acute Severe Hypoxia in Gats
Authors: Thorén Peter
Published: December 2008

In chloralose anesthetized cats blood pressure, heart rate and left ventricular pressure were measured as well as changes in ventricular volume by means of a cardiometer. Hypoxia was induced by ventilating the animal with a gas mixture containing 3 % O2. 1–2 min after the onset of hypoxia cardiac volume started to increase and simultaneously a bradycardia developed. The bradycardia was eliminated by vagal cooling indicating that it was elicited by nervous mechanisms rather than by local myocardial factors. After injection of procaine (0,3–0,5 %) into the cardiometer the afferent vagal fibres from the ventricles could be blocked, leaving the efferent fibres to the sinus node intact. Such selective denervation of the ventricular receptors markedly reduced the bradycardia during hypoxia, suggesting that it is mainly a reflex response emanating from ventricular receptors.
Dual Effects on the Sphincter of Oddi and Gallbladder Induced by Stimulation of the Right Great Splanchnic Nerve
Authors: Persson Carl G. A.
Published: December 2008

The right great splanchnic nerve was stimulated in 15 anesthetized cats. Effects on gallbladder pressure, resistance to flow through the sphincter of Oddi, and (in 6 cats) intramural duodenal pressure were evaluated. By nerve stimulation, the sphincter was consistently contracted and the intestine relaxed. The gallbladder showed variable slight responses, except in 3 cats where consistent relaxation was obtained. Cholecystokinin (i.v.) relaxed the sphincter and contracted the gallbladder. During the action of the hormone, the nervous response was counteracted in the sphincter; in the gallbladder, relaxation was obtained in all cats. Noradrenaline (i.v.) mimicked the responses induced by adrenergic nerve stimulation. The contraction of the sphincter induced by nerve stimulation and by noradrenaline was inhibited by phenoxybenz‐amine and atropine. The relaxation of the gallbladder was prevented by propranolol. It is concluded that the adrenergic splanchnic nerves, as well as i.v. noradrenaline, mainly activated α‐receptors in the sphincter of Oddi (inducing contraction) and β‐receptors in the gallbladder (inducing relaxation). Results obtained with the nerve stimulation and the 3 blocking agents also confirmed the presence of contraction‐mediating atropine‐sensitive cholinoceptors in the sphincter and the gallbladder, contraction‐mediating α‐receptors in the gallbladder, and relaxation‐mediating β‐receptors in the sphincter.