bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Effects on the Inflation Reflex during Expiratory Time in the Cat
Authors: Euler Curt von , Trippenbach Teresa
Published: December 2008

In order to obtain further information on the mechanisms controlling expiratory duration (TE) we have studied the effects of changes in body temperature on reflex characteristics of the TE‐prolonging inflation reflex. In cats under light pentobarbitone anesthesia controlled volume changes were applied at various times in expiration and the changes in TE were measured from records of phrenic activity. Inflations falling in the last 20% of the control expiratory time were without effect. This reflex insensitive phase remained a constant fraction of expiratory time when respiratory rate was changed with temperature. The relative reflex responsiveness increased, and the volume threshold was reduced with increasing respiratory rate. The inflation reflex characteristics showed integration of the incoming pulmonary stretch receptor activity. The integrating mechanism exhibited a ‘leaky’ character, the decay rate of which changed with body temperature. Functionally the duration of the inspiration‐inhibiting activity controlling expiratory duration can be regarded as dependent on 3 main factors 1) the initial peak level of the inhibitory activity, 2) the amount and timing of the vagal afferent activity which adds to this inhibition, and 3) its rate of decay. The results suggest that all these factors are influenced by changes in temperature.
Convergence on Interneurones Mediating the Reciprocal Ia Inhibition of Motoneurones
Authors: Hultborn H. , Illert M. , Santini M.
Published: December 2008

Interneurones identified as mediating the disynaptic reciprocal Ia inhibition of motoneurones (referred to as “Ia inhibitory interneurones”) were recorded in the lumbar spinal cord of the cat. Volleys in ipsilateral and contralateral high threshold muscle afferents, cutaneous afferents and high threshold joint afferents evoked a mixture of polysynaptic excitation and inhibition. These effects were ascribed to pathways activated by flexor reflex afferents (FRA) and in addition a specific ipsilateral low threshold cutaneous pathway. Ia inhibitory interneurones excited monosynaptically from flexor nerves received stronger net excitation by volleys in ipsilateral FRA than did extensor coupled interneurones, while the opposite pattern was seen from the contralateral FRA. These patterns are similar to those found in flexor and extensor motoneurones respectively. The FRA inhibition in Ia inhibitory interneurones was partly mediated by “opposite” Ia inhibitory interneurones, i.e. those which are mediating the Ia inhibition of la inhibitory interneurones. The extent to which the FRA inhibition is transmitted by Ia inhibitory interneurones was roughly estimated by its susceptibility to recurrent depression by antidromic ventral root stimulation. The main conclusion is that most segmental pathways seem to evoke their effects in parallel to motoneurones and Ia inhibitory interneurones which are monosynaptically linked to the same muscle. The functional importance of this conclusion is discussed in a following report.
Inhibition by Reserpine, Guanethidine and Imipramine of the Uptake of 5‐Hydroxytryptamine by Rat Peritoneal Mast Cellsin Vitro
Authors: Gripenberg J.
Published: December 2008

The effect of reserpine, guanethidine and imipramine on the uptake of tritiated 5‐hydroxytryptamine by rat peritoneal mast cells was studiedin vitro.The Kmvalue for uptake of 5‐hydroxytryptamine was 3 × 10‐7M in this study. Kinetic analysis of the data obtained suggests that the drugs inhibit the uptake in a competitive manner, in the order of decreasing potency: reserpine, imipramine, guanethidine. For reserpine the Dixon plot resulted in two curves, each composed of 2 linear components suggesting inhibition of uptake of 5‐hydroxytryptamine at 2 different levels or by 2 different mechanisms with different K1values. It is suggested that the higher K1value, representing an immediate effect of reserpine, stands for inhibition of uptake at the cell membrane. The lower K1value possibly represents inhibition at the level of the membranes surrounding the intracellular storage organelles.
The Vagal Control of the Ileo‐Cecal Sphincter in the Cat
Authors: Pahlin P.‐E. , Kewenter J.
Published: December 2008

In acute experiments on chloralosed cats the effect of efferent cervical vagal stimulation on a flow through the ileo‐cecal sphincter (ICS) was studied. The motor activity of the jejunum, ileum and large intestine adjacent to the sphincter was recorded simultaneously. Vagal stimulation caused a decrease in the transsphincteric flow and increased motor activity in the ileum. Increased motor activity in the proximal colon was recorded only occasionally. When the vagal nerves were stimulated during continuous splanchnic stimulation the transsphincteric flow was decreased although the tone and motility of the ileum was supposed. Furthermore, guanethidine (1–3 mg/kg b.w.) blocked or suppressed the effect of vagal stimulation on the transsphincteric flow while the excitatory response of the proximal colon was greatly enhanced. This indicates that the reduction of the transsphincteric flow following vagal stimulation was at least partly due to a direct effect of the vagal nerves on the sphincteric muscle and not to a squeezing effect of that part of the colonic wall that surrounds the sphincter. Atropine (0.1 and 1 mg/kg b.w.) blocked all responses to vagal stimulation. Thus, both guanethidine and atropine blocked the vagally induced contraction of the ICS. Relaxation of the ICS was never obtained by vagal stimulation even when the tone of the sphincter had been increased by infusion of noradrenaline.
Effects of Lanthanum on Pinocytosis Induced by Cations inAmoeba proteus
Authors: Josefsson J.‐O. , Hansson S. Elisabeth
Published: December 2008

Lanthanum chloride (≥ 10‐5M) induced pinocytosis in normal and at ≥10‐4M in Ca++‐deficient amoeba. With respect to the Ca++‐requirement of the pinocytotic response low and high concentrations of La+++had effects like Na+and K.+, respectively. The concentration of La+++and the concentration and species of inducing monovalent cation determined whether La+++stimulated or inhibited other types of pinocytosis. Thus all concentrations of La+++inhibited sodium induced pinocytosis while high concentrations (> 10‐3M) stimulated and low concentrations diminished potassium induced pinocytosis. Only the latter effect required the presence of Ca++. In the presence of La+++other inducers acted either like K+or Na+. Inducers may cause channel formation by opening a pore for Ca++in the plasma membrane, Na+‐like inducers being less effective than K+‐like inducers, and by releasing Ca++into the cytoplasm from the glycocalyx (Na+‐like inducers) or from the entire cell membrane (K+‐like inducers). La+++may diminish the effect of Na+‐like inducers and vice versa by direct competition for sites in the glycocalyx and the effect of K+‐like inducers by redistribution of Ca++in the cell surface. At high concentrations or in the presence of a K+‐like inducer La+++may enter the Ca++pore, release Ca++from the interior of the membrane and so induce or stimulate pinocytosis.
The Effect of Local Application of Vinblastine or Colchicine on Acetylcholine Accumulation in Rat Sciatic Nerve1
Authors: Heiwall P.‐O. , Saunders N. R. , Dahlström A. , Häggendal J.
Published: December 2008

The accumulation of acetylcholine (ACh) following nerve crush was inhibited by high concentrations of colchicine (10‐1, 10‐2 M) and vinblastine (10‐2‐10‐4 M) in a dose‐dependent manner. The two mitotic inhibitors were effective both when applied to axons (subepineural injections) and to perikarya (injections into the lumbar intumescence). The results indicate that mitotic inhibitors, when applied locally to cholinergic motor neurons, may block the proximo‐distal transport of ACh. The possibility is discussed that this blockade is caused by an interference with a microtubule mechanism in the axons. Evidence for an increased local synthesis of ACh near the site of injection into nerves was also obtained with the highest concentrations of either substance used.
Release of Vitamin B12‐Binding Protein from Isolated Rat Liver Perfused with a Synthetic Medium
Authors: Nováková Vera , Gullberg Ragnhild
Published: December 2008

The unsaturated vitamin B12‐binding capacity (UBBC) of the small molecular size vitamin B12‐binding protein (SBP) release and albumin release into the medium and the fluid pressure in the portal vein were studied with respect to their ability to reflect the state of isolated perfused rat liver. The liver was perfused in vitro with a synthetic medium either with or without a gas carrier. Liver damage was induced by hypoxia or noradrenalin. Variations in experimental conditions resulted in different patterns of parameters reflecting different aspects of the liver state. The fluid pressure in the portal vein reflected sensitively the circulatory state but is not always a criterion of the general condition of the isolated liver. The albumin release is a criterion of functional state but did not always reflect liver damage. However, the amount of UBBC of SBP released into the medium is a parameter reflecting sensitively the functional capacity of the liver to produce protein and also seems to indicate liver damage. The use of this parameter provides supplementary information that cannot be obtained by either of the two more conventional parameters.
Motor and Secretory Effects of Nerves on the Parotid Gland of the Rat
Authors: Thulin Anders
Published: December 2008

The influence of parasympathetic and sympathetic nerves on the parotid gland of the rat was investigated. It was found that both divisions of the autonomic nerves evoke secretion and probably also motor effects in this gland. Secretion elicited on sympathetic stimulation was mediated both via α‐ and β‐adrenoceptors, while motor effects were mediated via α‐adrenoceptors. On stimulation of the autonomic nerves a lower duct pressure was reached in the parotid than in the submaxillary gland, and on sympathetic nerve stimulation the flow of saliva always started later from the parotid than from the submaxillary gland. These findings are discussed in the view of the different arrangement of the myoepithelial cells in the 2 glands.
Anin vitro‐Formed Protamine‐Heparin Complex as a Model for a Two‐Compartment Store for Biogenic Amines
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo
Published: December 2008

The capacity of anin vitro‐formed protamine‐heparin complex (PHC) to store inorganic cations and biogenic amines was investigated. The PHC behaves like a two‐compartment storage system. One compartment corresponds to the terminal free carboxyl groups of the protamine moiety and has the characteristics of a cation exchanger, with the ability to bind inorganic cations and biogenic amines in a reversible and rather unselective manner. The cations and biogenic amines therefore compete for and displace each other from the common ionic binding sites. The binding sites in the other compartment, corresponding mainly to the carboxyl groups of the heparin moiety, are only unmasked at high ionic concentrations and show a specific affinity for biogenic amines. The storage of amines in this compartment of the PHC is reversible but is dependent not only on simple ionic binding but evidently also on other attractive forces, such as dipole and hydrogen bonding.
Gravitational Stress and Autonomic Cardiac Blockade
Authors: Bjurstedt H. , Rosenhamer G. , Tydén G.
Published: December 2008

Arterial pressure, heart rate and cardiac output were recorded in eight healthy, male volunteers in the sitting position at normal gravity (1 G) and during a 4 min exposure in a human centrifuge to 3 G, the G vector in both conditions acting in the head‐foot direction. The responses of the observed variables to the change from 1 G to 3 G were compared before and after combined beta‐adrenergic and parasympathetic blockade of the heart induced by the i.v. administration of propranolol, 0.25 mg/kg bwt, and atropine, 0.03 mg/kg bwt. After blockade the heart‐rate response to increased G averaged 22% of that observed without blockade. Mean arterial pressure at 3 G, and thus G tolerance, was significantly lowered after blockade, resulting in symptoms of retinal hypoxia (“greyout”) towards the end of the 3 G runs in some of the subjects. G‐induced reductions in cardiac output and stroke volume were significantly larger after blockade. Associated increases in total peripheral resistance were 56% before and 79% after blockade, the stronger vasoconstrictor response in the latter case thus being insufficient for maintenance of arterial pressure homeostasis.
Interaction between the Hypothalamic Defence Reaction and Cardiac Ventricular Receptor Reflexes
Authors: Wennergren Göran , Lisander Björn , ÖBerg Bengt
Published: December 2008

The interference with regard to the cardiovascular and gastric motility responses which follows stimulation of the hypothalamic defence area (D.A.) and a simultaneous afferent input from cardiac ventricular receptors was analysed in chloralose‐anesthetized cats. In spinalized animals with only the vagal efferent innervation of autonomic effectors from supraspinal structures intact, a D.A. stimulation increased the heart rate to the same level irrespective whether the cardiac receptor afferents were stimulated or not. This suggests that the vagal component of the reflex bradycardia of cardiac receptor origin was completely suppressed by the D.A. stimulation. The reflex gastric relaxation to cardiac receptor activation, mediated via vagal efferent non‐adrenergic fibres, was similarly completely blocked by D.A. stimulation. In contrast, the reflex inhibition of the sympathetic outflow to the heart and vessels from cardiac receptors was still effective during a D.A. stimulation, a phenomenon which seems compatible with a simple summation of excitatory D.A. and inhibitory cardiac receptor influences on the sympathetic neurons. The modifying influence from ventricular receptors on D.A. responses closely resembles that exerted by the arterial baroreceptors. The two reflex mechanisms thus work in concert and synergistically with the hypothalamic influences to produce maximal cardiac output and skeletal muscle perfusion without undue increases of pressure load on the pump during a defence reaction.
The Effects of Neuraminidase and Protamine Chloride on Potential Clamp Parameters of the Node of Ranvier (Xenopus laevis)
Authors: Frankenhaeuser B. , Ryan K. J. , ÅRhem P.
Published: December 2008

The effects of neuraminidase and protamine chloride on the ionic currents associated with step changes in membrane potential were studied. Neuraminidase (a hydrolase which cleaves glycosidically bound sialic acid) had negligible effects on the permeability properties. The polycation protamine chloride decreased the sodium as well as the potassium currents. The sodium equilibrium potential decreased during the experiments which indicates a gain in internal sodium concentration. The analysis showed that the effects on the currents were caused by a decrease of the specific permeability changes. No shift along the potential axis of the potential dependent parameters was observed.
Glucose Consumption in Rat Cerebral Cortex in Normoxia, Hypoxia and Hypercapnia
Authors: Borgström L. , Norberg K. , Siesjö B. K.
Published: December 2008

Glucose consumption was measured in the cerebral cortex of rats, anesthetized with 70% N2O, under normoxic conditions, as well as in hypoxia (Pao2 about 25 mmHg) and hypercapnia (Paco2 80–85 mmHg). The method used was that of Hawkins et al. (1974), modified to allow studies of transients in glycolytic rate. Cortical glucose consumption in normoxia was 0.77 μmol·g‐1·min‐1. It is concluded that whereas glucose consumption in the whole brain of the unanesthetized rat may be close to 0.6 μmol·g‐1·min‐1, that of the cerebral cortex is close to 0.8μmol·g‐1·min‐1. During the first 2 min of hypoxia, glucose consumption was increased to twice the normal, and during the first 2 min of hypercapnia, the corresponding value was less than one third of the normal. After 15 min of hypoxia, the glucose consumption had returned towards control values. In “steady state” hypercapnia, the glycolytic flux was higher than in the initial phase although still below normocapnic values.
Solubility of Xenon in Rat Hair
Authors: Malchow‐Møller Axel , Madsen Joop
Published: December 2008

The use of 133Xe in tracer washout techniques for measurements of local perfusion coefficients has necessitated determination of 133Xe solubility in various tissues (Isbister et al. 1965, Kitani 1972, Veall and Mallett 1965, and Yeh and Peterson 1963, 1964 and 1965). In studies on Xe elimination from adipose tissue, rats were enclosed in an atmosphere containing 133Xe. The unexpected finding of a considerable 133Xe activity in the fur prompted the present determination of Xe solubility in rat hair.
Protein Synthesis with Special Reference to S‐100 Protein in Brain Slices from Rats Receiving a Restricted Protein Supply
Authors: Wroński Andrzej , Decken Alexandra von der
Published: December 2008

The synthesis of S‐100 protein and that of soluble and total proteins was investigated using cerebral slices from rats fed a 20% or 3% protein containing diet for 6 days. Incorporation of radioactive amino acids into S‐100 protein was significantly higher when rats were fed a diet containing 20% protein. No significant differences were obtained in the radioactivity incorporated into total or soluble proteins between the 2 dietary groups. 14C‐leucine of a specific radioactivity of 55 mCi/mmol or 3.2 mCi/mmol incorporated with time into total protein was similar for the 2 dietary groups. The time‐dependent uptake of 14C‐leucine by the slices and the inulin space remained unaffected by the dietary conditions used; and amino acid analyser estimates of the free amino acid pool showed no significant differences. Brain wet weight was 1.54 ± 0.02 g and 1.39 ± 0.02 g for protein‐fed and protein‐restricted rats respectively. The corresponding body weight increased by 7.8 g/day or fell by 0.5 g/day. Although the differences observed in total protein synthesis were small the synthesis of a nervous tissue specific protein S‐100 was markedly affected by short‐term protein restriction.
Oxygen Uptake and Tissue Oxygen Tension during Adrenergic Stimulation in Canine Subcutaneous Adipose Tissue
Authors: Fredholm Bertil B. , Linde Birgitta , Prewitt Russell L. , Johnson Paul C.
Published: December 2008

The effect of sympathetic nerve stimulation (NS) and injected noradrenaline (NA) or isoprenaline (Iso) on PvO2, V̇osand PtO2was studied in isolated canine subcutaneous adipose tissue. These effects were compared to those produced by mechanical blood flow reduction (clamping). Resting V̇o2measured 13.0 ± 2.3 μmol × min‐1× 100 g‐1. When blood flow was reduced by 20% or less there was no significant change of V̇o2. Reducing blood flow to 50% of control or less by NS caused a parallel reduction in V̇o2, while clamping reduced V̇o2significantly less. NA gave effects similar to those of NS. After NS or NA there was a period of hyperemia and increased oxygen extraction which more than compensated for the decrease in V̇o2during vasoconstriction. Such a net increase in V̇o2was not produced by clamping. Control PtO2averaged 29±2 mmHg. NA reduced it by 70% and clamping to the same blood flow level only by 14% (p<0.01). Thus, a mere reduction in blood flow has little effect on PtO2, while blood flow reduction combined with redistribution of blood flow and an increased oxygen demand can lead to tissue hypoxia.
Prediction of Propagation Block on the Basis of Impulse Shape in Single Unit Recordings from Human Nerves
Authors: Vallbo Å. B.
Published: December 2008

The occurrence of impulse block was studied in single unit recordings and related to impulse shape when peripheral nerves were impaled with tungsten needle electrodes. Exposed nerves were exploited in frog and cat and non‐exposed nerves in man. Three different impulse shapes were seen: 1. Negative spikes of very short durations which nearly all propagated. 2. Positive double peaked spikes which all propagated. 3. Positive single peaked spikes which were of two different natures: one which propagated and one which did not. The findings suggest that unitary impulses recorded with a needle electrode impaling the myelin are positive and single peaked when the injury is minimal. Gradually a propagation delay might develop at the site of impalement giving rise to a double peak. Later the propagation may be blocked which is seen as a drop out of the second peak. The collected sample of observations indicates that it was possible to predict in practically all cases whether the propagation was blocked or not from the shapes of the single unit impulses and their alterations as seen by the tungsten needle electrode.
Effect of Vasodilating Drugs on External Carotid and Pulpal Blood Flow in Dogs: “Stealing” of Dental Perfusion Pressure
Authors: Tönder K. J. H.
Published: December 2008

Blood flow in the external carotid artery (ECBF) and dental pulp (PBF) was measured during arterial infusion of vasodilators (isoprenaline, papaverine, acetylcholine and bradykinin). Systemic arterial pressure (AP) and local arterial pressure of the teeth (LAP) were recorded in a femoral and the lateral nasal artery respectively. All four vasodilators were found to increase ECBF and simultaneously reduce lateral nasal arterial pressure—or in other words—to “steal” perfusion pressure from the teeth. AP remained practically unchanged whereas PBF was variably affected. During infusion of isoprenaline PBF decreased on average by 19% of control. Papaverine nearly doubled PBF, while bradykinin caused no consistent change. Great pulpal flow variations were often recorded during constant acetylcholine infusion rate. The variable effect of the four vasodilators on PBF could partly be explained by the fall in LAP. Calculated pulpal resistance (LAP/PBF) showed no consistent change during isoprenaline infusion, bradykinin caused a slight fall and papaverine reduced LAP/PBF by 49%. The experiments demonstrate that due to the “stealing” of dental perfusion pressure caused by vasodilation in the neighbouring tissues, the effect of vasodilators on pulpal resistance vessels cannot be estimated without knowledge of the pressure in the small arteries directly feeding the teeth.
β2‐Adrenoceptors Facilitating Noradrenaline Secretion from Human Vasoconstrictor Nerves
Authors: Stjärne Lennart , Brundin Jan
Published: December 2008

Isolated superfused biopsy specimens of human peripheral arteries and veins, preincubated with 3H‐(‐)‐noradrenaline (NA) to label the neural stores of NA, were used to study the β‐adrenoceptors previously found to increase the secretion of 3H‐NA evoked by electrical field stimulation of the adrenergic nerves of this tissue. The increase in nerve stimulation induced secretion of 3H‐NA caused by 0.04μM isoprenaline was prevented by 1 μM propranolol. This &bT‐blocking drug by itself slightly but significantly depressed the secretion of 3H‐NA caused by nerve stimulation in the absence of isoprenaline. While the secretion of 3H‐NA was not affected by two known β1‐agonists, it was dose‐dependently and reversibly increased by two different β2‐agonists. The effect of isoprenaline on 3H‐NA secretion was not altered by a selective β‐antagonist, but strongly reduced or abolished by a β2‐blocking drug. The results indicate that the β‐adrenoceptors involved in the control of NA secretion from the vasoconstrictor nerves of human omental blood vessels are only to a minimal extent stimulated by NA secreted from the nerves, and therefore do probably not mainly serve to mediate local positive feedback control of transmitter secretion; the receptors appear to be β2 in nature.
Vagal Reflexes in the Bronchoconstriction Occurring after Induced Intravascular Platelet Aggregation
Authors: Vaage Jarle
Published: December 2008

Intravascular platelet aggregation induced in cats by i.v. infusions of collagen caused a transient increase in pulmonary vascular resistance (PVR) and in non‐elastic pulmonary resistance (RL), and a transient decrease in dynamic lung compliance (dyn CL). PVR, dyn CL and platelet aggregation after collagen infusions were unaffected by bilateral cervical vagotomy and atropinization, whereas these procedures reduced the post‐infusion rise in RL by about 50 per cent. The administration of indomethacin inhibited platelet aggregation as well as bronchoconstriction after collagen infusion. The present investigation indicates that intravascular platelet aggregation will cause reflex bronchoconstriction mediated by vagal efferent fibres.
The Origin of Impulses Recorded from Dentinal Cavities in the Tooth of the Cat
Authors: Haegerstam G.
Published: December 2008

Intradental nerve impulse activity can be recorded by means of electrodes inserted into dentinal cavities in the tooth of the cat. The following study has been conducted to investigate the origin of this impulse activity. The results suggest that the fibres from which the impulses are recorded must pass through the major part of the pulp between the recording electrodes. Furthermore, the results show that it is not possible to record discharges in the finest terminal branches in the pulpo‐dentinal border zone using the present technique. However, the data obtained indicate that these terminal branches were activated during stimulation resulting in recordable propagated axonal impulses.
Metabolic Reactions to Changes in Core and Skin Temperature in Man
Authors: Nielsen Bodil
Published: December 2008

The metabolic cold response, i.e. the increase in oxygen consumption above that for the given activity in a neutral environment, was measured in 7 subjects during cooling, resting or swimming in cold water (14, 16, 18, 20°C) and during rewarming in air (Ta 20, 30, 40°C), bicycling or resting. Esophageal temperatures varied between 38 and 34°C. Mean skin temperature was considered as equal to water temperature during cooling, and ranged between 25–35°C during rewarming in the different environments. Both central and peripheral cold stimulation induced metabolic cold responses. The skin temperature was the dominating factor in determining the response, especially in transient states. During rewarming a rising skin temperature suppressed the effects of even very low core temperatures.
The Role of Cholinergic Excitation in the Formation of Histamine within the Rat Gastric Mucosa
Authors: Lundell Lars
Published: December 2008

In the absence of the antrum, central vagal excitation and distension of the stomach accelerated the rate of formation of gastric mucosal histamine. The effect of vagus stimulation was abolished by truncal vagotomy or atropine whereas that of distension by atropine. After truncal vagotomy, distension was still effective in accelerating the formation of the amine. Furthermore, mucosal histamine formation in the fasting state was reduced by truncal vagotomy and atropine injection.
Effects of Respiratory Alkalosis and Acidosis on Myocardial Excitation
Authors: Samuelsson Rolf G. , Nagy György
Published: December 2008

In anesthetized dogs electrocardiogram and monophasic action potentials (MAPs) were recorded from the right atrium and the right ventricle by intracardiac suction electrode technique. The animals were subjected, by means of ventilation with CO2 and hyperventilation, to periods of respiratory acidosis and respiratory alkalosis, respectively. Pronounced respiratory acidosis induced an increased sympathetic activity followed by a decrease in heart rate and prolongation of the A‐V conduction time whereas the shape and duration of the atrial and ventricular MAPs remained unaltered. Arterial hypoxia in combination with pronounced respiratory acidosis did not influence the MAP durations. Respiratory alkalosis resulted in an increased sympathetic influence on the heart activity whereas the shape and duration of the atrial and the ventricular MAPs remained unaffected. During pronounced hyperventilation with increasing central venous pressure an increased parasympathetic influence on the heart activity with decrease in the heart rate, prolongation of the A‐V conduction time and shortening of the atrial MAP duration was recorded.
Effect of Sympathetic Nerve Stimulation on Net Transvascular Movement of Fluid in Canine Adipose Tissue
Authors: Linde Birgitta
Published: December 2008

Net transvascular movement of fluid has been studied in the isolated, autoperfused subcutaneous adipose tissue of the dog, during and after sympathetic nerve stimulation (1–15 Hz) and during infusion of 50% glucose i.a. Net fluid movement was calculated as the difference between change in tissue volume and change in blood volume. Tissue volume was measured by plethysmography and blood volume by external monitoring of circulating131I‐albumin. No net fluid movement of statistical significance was found during or after nerve stimulation except during the first minute of stimulation at 15 Hz when a small net absorption (p<0.05) was obtained. In contrast, infusion of glucose at 25–75 mOsm/kg H2O produced a dose‐dependent net absorption lasting several minutes, amounting maximally to 0.30 ml × min‐1× 100 g‐1. The absence of prolonged net absorption in subcutaneous adipose tissue during nerve stimulation as well as the absence of net filtration after stimulation may be explained by an essentially unaltered mean hydrostatic capillary pressure. The results indicate that adipose tissue does not contribute to the fluid homeostasis of the body via sympathetic resetting of the pre‐postcapillary resistance ratio. Thus, mobilisation of fluid from the nterstitial space in adipose tissue into the blood does not seem to occur by nerve activity.
Effect of the H2‐Receptor Antagonist Metiamide on Carbachol‐and Histamine‐Induced Gastric Acid Secretion in the Atlantic Cod, Gadus morhua
Authors: Holstein Björn
Published: December 2008

Gastric acid secretion was measured in swimming codfish surgically equipped with a catheter draining the stomach. Intramuscular injection of histamine (15.6μg/kg·h) or carbachol (5μg/kg·h) stimulated the secretion of acid, carbachol in addition caused a marked decrease in drinking rate of the fishes. Administration of 10μmol/kg·h metiamide completely prevented the acid secretion induced by both drugs. The carbachol effect on the drinking rate, interpreted to mirror contraction of the stomach following stimulation of muscarinic receptors, was not affected by metiamide.
Influence of Altered CSF Solute Composition on Parotid Salivary Secretion in Goats
Authors: Olsson Kerstin
Published: December 2008

Infusions of hypertonic NaCl solution into the CSF of the lateral cerebral ventricle of the goat caused a marked reduction in parotid salivary flow concomitant with a rise in salivary [Na+]. Corresponding infusions of iso‐ or hypertonic glucose and glycerol solutions affected salivary secretion in the opposite direction. The possibility is discussed that a periventricular sodium‐sensitive mechanism, which is of importance in the central control of fluid balance, also may participate in the regulation of parotid secretion in the goat. This interpretation of the results is to some extent obscured by the observation of a high incidence of intermittent rumination during the intraventricular infusions of glucose and glycerol solution.
K+Transport in Isolated Rat Liver Cells Stimulated by Glucagon and Insulin in vitro
Authors: Berg Trond , Iversen Jens‐Gustav
Published: December 2008

Unidirectional K+fluxes were measured in suspensions of isolated rat liver parenchymal cells incubated with 42K+in vitro. By tracer exchange analysis fluxes in both directions were estimated to 8–9 10‐12mol/cm2. Glucagon in concentrations above 2 × 10‐8M increased both influx and efflux to 160% of control values. Insulin increased influx by 12–14 %, whereas efflux was apparently unaffected. Using an extracellular marker 51Cr EDTA, intracellular level of some ions was estimated in isolated liver cells: K+= 172 mmol/kg water, Na+= 25 mmol/kg water, CI = 53 mmol/kg water. Cellular water content: 60%. Incubation with insulin for 1 h increased the intracellular concentration of K+1.7 mmol/kg water. The results indicate that glucagon increases primarily the K+‐permeability of the cell membrane, while insulin stimulates active K+transport into the cell.
Sources of Carbon Skeleton of Alanine Released from Skeletal Muscle
Authors: Spydevold Ø.
Published: December 2008

The formation of alanine, glutamate, and aspartate from muscle was studied in the isolated perfused hind‐quarter of rats fasted for 48 h. Tracer doses of (14C) compounds with high specific activity were tested as precursors for the amino acids. Total amounts and radioactivities of the tested amino acids were determined. Alanine was produced more efficiently than glutamate and aspartate even if no exogenous substrate was offered. (14C) Pyruvate was most efficient as precursor of labeled alanine. However, labeled leucine, propionic acid, valine and fumaric acid also produced labeled alanine efficiently. The efficiency as precursor for labeled alanine seemed to be related to the ability to label intermediates in the citric acid cycle in the perfused muscle. From the relation between the ability to label alanine in the perfusion medium and lactate and succinate in the muscle it is suggested that pyruvate may be produced intramitochondrially and is efficiently transaminated to alanine in this compartment.
Muscle Spindle Control during Locomotor Movements Generated by the Deafferented Spinal Cord
Authors: Sjöström Anders , Zangger Peter
Published: December 2008

In acute spinalized (Th 12) cats, treated with DOPA, curarized or with all lumbosacral dorsal roots transected, stepping patterns were elicited in the hindlimbs by continuous electrical stimulation of the dorsal roots. Single primary endings in dorsal root filaments or single γ and α efferents in muscle nerve filaments from flexors and extensors were recorded together with the efferent nerve activity to various hindlimb muscles. The experiments showed a clear coactivation of the intra‐ and extrafusal system to the same muscle. The α efferent discharges typically started with a very short first interspace interval. It is concluded that there exists a central spinal α‐γ‐Iinkage for locomotion in the hindlimbs.
The Effect of Nicotine on Intra‐Axonal Transport in Cholinergic Motor Neurons of the Rat; Influence of Acutely Administered, Non‐Toxic Doses
Authors: Heiwall P.‐O. , Dahlström A. , Larsson P.‐A.
Published: December 2008

The intra‐axonal transport of acetylcholine (ACh) and ACh‐metabolizing enzymes in rat sciatic nerves was studied following nicotine treatment. The nicotine was administered in a low dose (30;μg/kg) s.c. every second h for 18–22 h, to mimic the serum‐concentrations of a cigarette smoker. Control rats received s.c. injections of the vehicle. The main effects were observed regarding the ACh‐esterase (AChE) activity. In unoperated nerves the level was decreased by about 10%. In 12 h crushed nerves the accumulation of enzyme activity proximal to the crush was markedly reduced in the nicotine‐treated group, indicating a reduction in amount of proximo‐distally transported enzyme activity. The ACh‐levels were unchanged except at 12 h postoperatively when a small increase proximal to the crush was observed. The choline‐acetyltransferase (CAT) activity in unoperated nerves was similar in both groups of rats; the 7 h accumulation above the crush, however, was somewhat reduced after nicotine treatment. The possible causes of the observed nicotine induced changes are so far not known.
Influence of Acidosis on Noradrenaline‐Induced Vasoconstriction in Adipose Tissue and Skeletal Muscle
Authors: Hjemdahl Paul , Fredholm Bertil B.
Published: December 2008

Vasoconstriction due to parallel i.a. injections of NA were studied in subcutaneous adipose tissue and gracilis muscle preparations in dogs. The vasoconstrictor response to NA was significantly lower in adipose tissue than in muscle. Only in muscle did acidosis inhibit NA‐induced vasoconstriction. The β‐receptor antagonist propranolol increased the vasoconstrictor response in adipose tissue to the level of skeletal muscle. The lack of significant inhibition of NA‐induced vasoconstriction in adipose tissue may be due to the simultaneous inhibition of two opposing mechanisms‐α‐adrenergic vasoconstriction and β‐adrenergic vasodilatation. After propranolol acidosis inhibited NA‐induced vasoconstriction equally in adipose tissue and muscle. The difference between adipose tissue and muscle may thus be due to a greater importance of a β‐adrenergic vasodilator mechanism in the former tissue. The metabolic response to isoprenaline was inhibited by acidosis, while the direct vasodilatation was unaffected. It is suggested that the β‐adrenergic vasodilator mechanism that is inhibited by acidosis is related to the metabolism of the tissue.
Exteroceptive Influences on the Lumbar Back Muscle Tone and Reflexes in the Cat
Authors: Carlson Hans , Lindquist Christer
Published: December 2008

The exteroceptive influences on tonic activity and on stretch reflexes of the longissimus dorsi and multifidus spinae muscles were investigated in decerebrate, spinal and chloralose‐anesthetized cats. Adequate skin stimulation was used to map out facilitatory and inhibitory skin areas on the trunk and the extremities. On the trunk facilitatory areas are relatively large and located at the dorsal side while inhibitory areas are confined to the ventrolateral part of the contralateral body half. The facilitatory skin fields are of approximately the same size in decerebrate and spinal cats. On leg skin stimulation facilitation can be evoked from the ipsilateral hind limb while inhibition results from stimulation of the other limbs. Spinal cord transection increased excitatory effects of ipsilateral hind limb stimulation. Reflex responses in the back muscles to applied stretch are described. These reflexes were used as test reflexes in experiments with conditioning stimulation of the peripheral nerves supplying skin areas from which effects on back muscle activity were evoked by adequate stimulation. The conditioning‐test experiments and those using adequate stimulation show that the longissimus dorsi and multifidus spinae are activated or facilitated by an ipsilateral stimulus to skin afferents. The extent of the effects induced by stimulation of skin differs in the types of preparation used. These differences may be accounted for by assuming a supraspinal control of the reflex pathways studied.
Secretory and Motor Effects in the Submaxillary Gland of the Rat on Intraarterial Administration of Some Polypeptides and Autonomic Drugs
Authors: Thulin Anders
Published: December 2008

Bradykinin, oxytocin, physalaemin and some autonomic drugs were injected into the common carotid artery. Physalaemin evoked secretion and a pressure rise in the submaxillary duct. A duct pressure rise could be elicited by bradykinin which did not evoke secretion. Autonomic blocking agents did not diminish secretion evoked by physalaemin and did not change pressure responses elicited by bradykinin or physalaemin. Neither secretion, nor duct pressure changes could be recorded after administration of oxytocin. In agreement with previous experiments secretion evoked by autonomic drugs was found to be mediated via cholinergic, α‐ and β‐adrenergic receptors, while motor effects were due to activation of cholinergic and a‐adrenergic receptors.
Gastric Clearance of Gastrin during Acid Secretory Responses to Vagal Activation and its Effect on Peripheral Gastrin Levels A Study on Anesthetized Cats
Authors: Uvnäs‐Wallensten K. , Uvnäs B.
Published: December 2008

Gastrin release and gastric acid secretion were induced by electrical stimulation of the vagi in anesthetized cats. No correlation was found between the peripheral gastrin levels and the magnitudes of the concomitant secretory responses. In experiments in which a high rate of secretion was induced the peripheral gastrin levels were found to be unchanged or at most slightly elevated, whereas the levels were sometimes substantially elevated in animals in which there was little or no acid secretory response.

An arterio‐venous difference in gastrin levels was detected in the corpus blood during periods of gastric secretion. This clearance of gastrin (104–540 pg/min) was large enough to influence the peripheral gastrin levels. The mechanism behind and the significance of the gastric clearance of gastrin is discussed.
Liver and Heart Mitochondrial Succinate Dehydrogenase Activity of Newborn Rats in Anoxic Hypoxia and Starvation
Authors: Kinnula Vuokko L. , Juujärvi Kyösti
Published: December 2008

Succinate dehydrogenase activity was determined in the liver and heart of newborn rats after 3 and 48 hours' exposure to anoxic hypoxia (10% O2) and after 48 hours' starvation. Control determinations were made on newborn animals of corresponding ages, full term foetuses (21 days), infantile (1 and 2 weeks) and full grown animals. Hypoxia for 3 h had no influence on succinate dehydrogenase activity at all in either the heart or liver mitochondria of the newborn animals. After 48 h no difference was observed in the liver between the hypoxic animals and the starved controls of the same age, though starvation itself had resulted in a significant increase in activity, as much as 42%. When liver mitochondrial succinate dehydrogenase in normal mitochondria was activated by preincubation mitochondria with the substrate, the activity increase obtained was greater than that resulting from starvation. The increase in activity in the heart of the hypoxic or starved animals was not significant (< 10%).
Vagal Influence on Serotonin Concentration in Enterochromaffin Cells in the Cat
Authors: Ahlman H. , Dahlström A. , Kewenter J. , Lundberg J.
Published: December 2008

The intracellular concentrations of 5‐HT in enterochromaffin cells of the jejunum, midgut and ileum of the cat have been estimated by a cytofluorimetric method before and after various periods of peripheral vagal nerve stimulation. The fluorescence intensities in randomized cell samples were measured photometrically after a standard illumination time before and after nerve stimulation. A significant decrease in 5‐HT concentration in the enterochromaffin cells all through the small intestine could be demonstrated, which is in support of the hypothesis of a neurogenic release of 5‐HT from enterochromaffin cells, possibly caused by vagal adrenergic fibres.
Prostaglandins, a Link between Renal Hydro‐ and Hemodynamic in Dogs
Authors: Olsen Uffe Bang , Magnussen Magnus Pauli , Eilertsen Eva
Published: December 2008

An increase of the intrarenal pressure to 40 mmHg induced by ureteral constriction or by kidney compression is shown to be followed by increased renal blood flow in anesthetized dogs. This hyperemia is probably the result of enhanced intrarenal prostaglandin activity since it is followed by increased urinary prostaglandin E excretion and is abolished by indomethacin pretreatment. The increase of renal blood flow seems to be due to dilation of the afferent arteriole in order to maintain the filtration pressure. The glomerular filtration rate is thus severely depressed in indomethacin pretreated dogs. Urine and electrolyte excretion is comparably reduced during elevated intrarenal pressure in non‐pretreated and in indomethacin pretreated dogs, which suggests that factors other than glomerular filtration rate are involved. Urine osmolarity is positively correlated with renal blood flow, and urine osmolarity increases during elevated intrarenal pressure in non pretreated dogs, whilst urine osmolarity remains unchanged in dogs pretreated with indomethacin.
Effect of Chronic Sympathetic Denervation upon Local Regulation of Blood Flow in Human Subcutaneous Tissue
Authors: Henriksen O.
Published: December 2008

The effect of chronic sympathetic denervation upon the vasoconstrictor response to an increase of vascular transmural pressure in human subcutaneous adipose tissue was investigated in 6 patients suffering from manual hyperhidrosis. Changes in transmural pressure were obtained either by postural changes of a forearm or by venous stasis of 30 mmHg. Blood flow was measured in the distal part of the forearm or crus by means of the local133Xenon washout technique. 2 patients were studied before and after sympathectomy. When the area under study was lowered about 40 cm below the jugular notch, blood flow decreased about 50 per cent preoperatively, about 30 per cent 24 h after the operation, but remained constant 4 days after or later. Similar results were obtained during venous stasis. Hence about 4 days after sympathectomy, the vasoconstrictor response to an increase in vascular transmural pressure was abolished. In 3 chronically sympathectomized patients blood flow remained constant in the denervated limb, but decreased significantly in the control limb. In another patient studied 580 days after surgery blood flow remained constant during lowering of the denervated forearm as well as during venous stasis.

These findings might indicate that the vasoconstrictor response to an increase in vascular transmural pressure in human subcutaneous adipose tissue is due to a local nervous mechanism involving symphathetic adrenergic nerves, but a myogenic mechanism cannot be definitively excluded.
Local Nervous Mechanism in Regulation of Blood Flow in Human Subcutaneous Tissue
Authors: Henriksen Ole
Published: December 2008

The effect of local venous stasis upon blood flow in human subcutaneous adipose tissue on the distal part of the forearm was investigated in three healthy subjects and two chronically sympathectomized patients suffering from manual hyperhidrosis. The area under study was separated into two parts by means of a lead shield exerting a pressure of about 360 mmHg on the skin. The effect of venous stasis of about 40 mmHg on one side of the shield upon blood flow measured simultaneously on both sides of the shield by the local 133Xenon washout technique was investigated. During venous stasis on one side of the shield, blood flow decreased about 40 per cent on both sides. The vasoconstrictor impulse could be transmitted over a distance of about 1–2 cm. The phenomenon was unaffected by nerve blockade induced 3 cm proximally, medially, and laterally to the area by infiltration the skin with lidocaine. Thus a vasoconstrictor impulse could be transmitted from the side of stasis to the non stasis side of the lead shield. The transmission was not affected by phentolamine but was blocked by lidocaine and chronic sympathetic denervation.

The vasoconstrictor impulse elicited during venous stasis is therefore most likely transmitted by means of a local nervous mechanism involving sympathetic adrenergic vasoconstrictor fibres.
Quantitative Measures of Enzyme Activities in Type I and Type II Muscle Fibres of Man after Training
Authors: Henriksson Jan , Reitman James S.
Published: December 2008

The effect of 7 to 8 weeks of physical training on oxidative and glycolytic enzyme activities in the 2 major fibre types of human quadriceps femoris muscle has been investigated. 2 groups of 4 and 5 subjects respectively were trained at the same total work‐load on a bicycle ergometer 3 days per week using interval exercise with maximal intensity (I.T.) or continuous exercise with submaximal intensity (C.T.). Succinate dehydrogenase (SDH) and phosphofructokinase (PFK) activities were determined on crude homogenates of muscle biopsy samples and on pools of type I and type II fibres dissected from freeze‐dried samples taken before and after training. Crude homogenate SDH activity increased to the same extent in both groups, average increases were 27.5% (I.T.) and 22% (C.T.), respectively. Only type I‐SDH increased in the C.T. group (p<0.01), the average increase being 32%. On the other hand only type II‐SDH increased in the I.T. group (p<0.01), with an average increase of 49%. No changes in PFK activity could be detected. The results of the present study emphasize the great adaptability in oxidative potential of both the two major human skeletal muscle fibre types and further that this adaptation seems to be related to the pattern of fibre recruitment during exercise.