bluuebunny/crossref_metadata_2025 huggingface dataset:
Renal capillary permeability and intravascular red cell aggregation after ischaemia. I. Effects of xanthine oxidase activity
Authors: ÖJTEG G. , BAYATI A. , KÄLLSKOG Ö. , WOLGAST M.
Published: December 2008

The macromolecular permeability of renal capillaries and the intravascular red cell aggregation resulting from 45 min of warm ischaemia were investigated. The effects of the xanthine oxidase inhibitor Allopurinol on these factors and also on the post‐ischaemic nephron function were also studied. Following ischaemia there was a more than 10‐fold increase in the transport from plasma to renal hilar lymph both of plasma proteins and of two isomers of lactate dehydrogenase (LDH)‐the nearly neutral LDH‐M4 and the negatively charged LDH‐H4. The ischaemia also resulted in massive intravascular red cell aggregation, especially in the renal medulla. Through reduction of plasma xanthine oxidase activity from 13.1 ± 1.1 μU μ1‐1 (mean ± SEM) to essentially zero by Allopurinol, the capillary leakiness was substantially diminished with almost complete normalization after 120 min. At the same time the relative volume of trapped red cells was reduced; in the inner stripe of the outer medulla, for example, it decreased from 11.3 ± 1.7% in untreated animals to 4.0 ± 1.1% after treatment with 20 mg of Allopurinol given intravenously 3 h before the ischaemia. Oral feeding with 4 mg of Allopurinol day‐1 for one week gave essentially the same result. The net driving force for filtration after treatment with this drug was thus 19 mmHg, as against 26 mmHg in the normal kidney and the resulting SNGFR was half the normal. The total filtration rate was proportionally more reduced to less than 1/3 of the normal. Tubular obstruction was still present but was not as severe as in untreated kidneys (Karlberg et al., 1982b) where the tubular fluid flow and thereby the filtration are essentially zero. It is suggested that oxygen free radicals increased the macromolecular permeability and the adhesiveness of white blood cells and that these two factors combined underlie the aggregation of red blood cells in the medullary vasa recta with consequent persistence of medullary ischaemia.
Galanin: effects on basal and stimulated insulin and glucagon secretion in the mouse
Authors: LINDSKOG S. , AHRÉN B.
Published: December 2008

Galanin was recently demonstrated to be a neuropeptide in intrapancreatic nerves. In this study, the effects of galanin on basal and stimulated insulin and glucagon secretion in the mouse were investigated. Galanin, injected intravenously at dose levels ranging from 0.53 to 8.5 nmol kg‐1, markedly lowered basal plasma insulin levels and transiently increased basal plasma glucagon levels. Furthermore, galanin induced hyperglycaemia: plasma glucose levels were 11 ± 0.2 mmol l‐1 2 min after injection of galanin (4.25 nmol kg‐1) compared with 9.3 ± 0.3 mmol‐1 in controls (P < 0.001). Galanin also impaired the plasma insulin response to either glucose or the cholinergic agonist carbachol. Thus, galanin (4.25 nmol kg‐1) inhibited the plasma insulin response to glucose by 65% (P < 0.001), and that to carbachol by 85% (P < 0.001). Moreover, glucose abolished the galanin‐induced plasma glucagon response. Also, galanin and carbachol exerted additive stimulatory effects on glucagon levels. It is concluded from this study in mice that galanin inhibits basal and stimulated insulin secretion, stimulates glucagon secretion, and induces hyperglycaemia. It is suggested that the intrapancreatic neuropeptide galanin is of importance in the regulation of both insulin and glucagon secretion.
Prolactin, AVP, angiotensin II, corticosterone and aldosterone in the rat during weaning
Authors: FINKEL Y. , SAHLGREN B. , ENEROTH P.
Published: December 2008

In the rat significant changes in the control of body water and electrolyte homeostasis take place during the weaning period (16–24th day of life). This study was performed to analyse how the serum levels of hormones that are known to modulate body water homeostasis change during that period. The serum levels of aldosterone, corticosterone and prolactin increased significantly from 10 to 20 days, whereas those of arginine vasopressin were the same between 10 days and 20 days but increased significantly from 10 to 40 days. Serum levels of angiotensin II increased significantly from 10 to 20 days but decreased from 20 to 40 days, at which time they were significantly lower than in 10‐day‐old rats. In prolonged‐suckling rats, that is, rats which suckled until the 20th day of life, the serum levels of corticosterone, aldosterone and prolactin were somewhat lower than in control rats and those of prolactin were not detectable at 16–20 days. It is concluded that important changes in the serum levels of hormones that regulate body water and electrolyte homeostasis take place during weaning. The postnatal increase in the serum levels of corticosterone and aldosterone is independent of weaning to solid food. The prolactin serum levels seem to be influenced by the length of the nursing period.
Cardiovascular effects of infused adenosine in man: potentiation by dipyridamole
Authors: CONRADSON T.‐B. G. , DIXON C. M. S. , CLARKE B. , BARNES P. J.
Published: December 2008

In a single blind randomized study, eight normal subjects (23–40 years) received on two separate days adenosine as a constant i. v. infusion with doses increasing from 0.005–0.1 mg kg‐1 min‐1 following either i. v. dipyridamole 0.4 mg kg‐1 per 10 min or a corresponding volume of saline. Heart rate, blood pressure and skin temperature were measured. Following saline all subjects tolerated adenosine 0.07 mg kg‐1 min‐1, six also tolerated 0.09 mg kg‐1 min‐1. Both heart rate and skin temperature increased with adenosine in a dose‐related manner. Thus, adenosine 0.09 mg kg‐1 min‐1 was associated with an increase in heart rate (mean ± SD) from baseline before saline with 16 ± 10 b. p.m. (P < 0.01) and an increase in skin temperature with 1.3 ± 0.8 °C (P < 0.02). Dipyridamole, which inhibits the cellular uptake of adenosine was associated with a change in heart rate similar to that induced by adenosine. Furthermore, when adenosine was infused following dipyridamole the changes in heart rate and skin temperature were potentiated as compared with adenosine following saline. Thus, following dipyridamole an increase in heart rate with 15 b. p.m. above baseline was obtained with 0.005 mg kg‐1 min‐1 of adenosine as compared with 0.08–0.09 mg kg‐1 min‐1 of adenosine following saline. Blood pressure did not change in any of the studies. Exogenous adenosine in man has a dose‐related positive chronotropic effect and a local dilatory effect in the skin microcirculation. Dipyridamole potentiates the cardiovascular effects of infused adenosine in man.
Differential stress effects on responses to noxious stimuli as measured by tail‐flick latency and squeak threshold in rats
Authors: HUANG K. H. , SHYU B. C.
Published: December 2008

In the present study tail‐flick latency (TFL) and squeak threshold (ST) were investigated in different environmental conditions in normotensive Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). The TFL did not vary significantly during the testing period (120 min). The ST increased gradually and significantly with time when measured in rats restrained in the TFL test tube. Freely moving rats transferred to the TFL test tube showed a marked decrease of the ST. During the stay in the TFL test tube, the ST value increased gradually. Also after transfer from the test tube to the home cage the threshold increased to the same level as freely moving rats. There were no significant differences in these effects between WKY and SHR. Naloxone (1 mg kg‐1i. v.) decreased the ST in both freely moving and restrained animals of either strain. Intravenous injection of morphine (mg kg‐1) gave a pronounced threshold increase of ST in both groups. It is suggested that animals restrained in the TFL test tube become hyperalgesic. The adaptation to stress is reflected in the ST but not in the TFL. Squeak threshold appears to be influenced by a tonically active endorphin system.
Enzyme levels of the NADH shuttle systems: measurements in isolated muscle fibres from humans of differing physical activity
Authors: SCHANTZ P.G. , HENRIKSSON J.
Published: December 2008

The aim of the present study was to investigate enzyme levels of the malate‐aspartate and alpha‐glycerophosphate shuttles in type I (slow‐twitch) and type II (fast‐twitch) fibres of human skeletal muscle. The influence of endurance training on these levels was also elucidated. Biopsy specimens were obtained from the lateral part of the quadriceps femoris muscle of six untrained and six endurance‐trained subjects.Type I vs. type II. In both groups the type I fibres exhibited higher levels of the TCA cycle marker enzyme citrate synthase (CS), as well as of the malate‐aspartate shuttle enzymes (cytoplasmic and mitochondrial malate dehydrogenase (cMDH, mMDH), and aspartate aminotransferase (cASAT, mASAT)).A more pronounced difference between type I and type II fibres was noted for cMDH (58%) than for mMDH (16%), cASAT (20%), mASAT (18%) and CS (25%). In contrast to these enzymes, the levels of cytoplasmic glycerol‐3‐phosphate dehydrogenase (cGPDH), the enzyme representative of the alpha‐glycerophosphate shuttle, were higher (25%) in the type II fibres.Endurance‐trained vs. untrained. In the endurance‐trained group, both fibre types were characterized by higher levels of CS (mean for both fibre types: 48%) as well as of mitochondrial malate‐aspartate shuttle enzymes (mMDH: 47%, mASAT: 48%) than in the corresponding fibre types in the untrained group, while the differences in the levels of cytoplasmic malate‐aspartate shuttle enzymes (cMDH: 13%, cASAT: 16%) were not statistically significant. Nor were the differences in cGPDH levels (8%) between the untrained and endurance‐trained groups statistically significant. It is concluded that in human skeletal muscle, malate‐aspartate shuttle enzymes are expressed to a higher degree in type I (slow) fibres than in type II (fast) fibres, with cMDH exhibiting the most marked difference. The single fibre analysis indicated that the muscle's activity level might exert a greater influence on the mitochondrial isoenzymes than on the cytoplasmic ones. In contrast to the malate‐aspartate shuttle enzymes, the alpha‐glycerophosphate shuttle is expressed to a higher degree in type II fibres and its capacity appears to not be influenced by endurance training. The present studies demanded considerable methodological investigations which also are presented in this paper.
Mechanisms involved in colonic vasoconstriction and inhibition of motility induced by neuropeptide Y
Authors: HELLSTRÖM P.M.
Published: December 2008

Neuropeptide Y (NPY) and noradrenaline are suggested to coexist as neurotransmitters in sympathetic neurons. The present study investigated the mechanisms involved in the colonic vasoconstriction and inhibition of motility induced by infusion of NPY and noradrenaline close i. a. Colonic blood flow was monitored using a drop recorder, and motility was registered by a volume recording device, both operating an ordinate writer. Colonic motility was stimulated either by electrical stimulation of the pelvic nerves (PNS; 4 Hz, 5 ms, 8 V) acting via enteric ganglia or by i. v.infusion of bethanechol (10 nmol kg‐1 min‐1) acting directly on muscarinic receptors on smooth muscle. With both types of motility stimulation, an immediate colonic vasodilatation was registered. Electrical stimulation of the lumbar colonic nerves (4 Hz, 5 ms, 8 V) induced colonic smooth muscle relaxation and vasoconstriction during continuous PNS (P < 0.05). Colonic contraction induced by PNS (P < 0.01) was dose‐dependently reduced by NPY (50–400 pmol min‐1; P < 0.05–0.01) and noradrenaline (1000–6000 pmol min‐1; P < 0.05–0.01). Simultaneously, vasoconstriction was induced by both NPY and noradrenaline (P < 0.01). Colonic contraction induced by infusion of bethanechol (P < 0.01) was not inhibited by NPY (50–200 pmol min‐1). However, at the highest dose (400 pmol min‐1) the motility response was reduced (P < 0.05). Similarly, noradrenaline only at the highest dose (6000 pmol min‐1) reduced the contractile response (P < 0.01). As before, vasoconstriction was induced by both NPY and noradrenaline (P < 0.05–0.01). As a further comparison, NPY and noradrenaline were administered prior to PNS or bethanechol. Infusion of NPY (200 pmol ml‐1) or noradrenaline (1000 pmol min‐1) efficiently prevented the motility response to PNS (P < 0.05) but not to bethanechol. During the administrations of NPY and noradrenaline vasoconstriction was induced (P < 0.05). The present findings imply that NPY, like noradrenaline, at lower doses inhibit colonic motility via an inhibition of excitatory enteric ganglia, whereas higher doses also exert a direct inhibitory action on colonic smooth muscle. However, the vasoconstrictor action of NPY and noradrenaline at both dose ranges is exerted directly on vascular smooth muscle.
Miosis and plasma prostaglandin E metabolites during endotoxin fever
Authors: JÓNASSON H.
Published: December 2008

The time course and intensity of miosis accompanying endotoxin (ET) fever was studied in goats concomitant with radio‐immunoassay of plasma PGE metabolites. The i.v. injection of ET (E. coli lipopolysaccharide; 0.25 μg kg‐1) induced a biphasic miosis correlated in time with the biphasic febrile response. Plasma PGE metabolites rose from an undetectable level to a mean of 2 nmol l‐1 during the early fever phase, but fell to an undetectable level during the second fever phase in spite of persisting pronounced miosis. Like light‐induced pupillary constriction, the ET miosis was antagonized by corneal application of atropine. A corresponding miotic response to ET was obtained also in the sheep. It is concluded that ET‐induced miosis requires cholinergic nerve conduction, and that its direct cause is not systemic liberation of PGE. It is suggested that rather some nervous or humoral stimulus developing in conjunction with ET fever acts upon the same brain stem locus as that mediating the pupillary light reflex.
Autoregulation of renal blood flow (RBF) with and without participation of afferent arterioles
Authors: OFSTAD J. , IVERSEN B. M. , MØRKRID L. , SEKSE I.
Published: December 2008

The participation of the afferent arterioles (AA) in RBF autoregulation was studied in two groups of rats (groups A and B) by measurement of the afferent arteriolar diameters (dAA) by the microsphere method at control pressure (groups A and B), at the lower pressure limit of RBF autoregulation (group A) and at a perfusion pressure half‐way between these pressures (intermediate pressure) (group B). The RBF was autoregulated from 109 ± 7 (control pressure) to 80 ± 7 mmHg (lower pressure limit) in group A, and from 101±4 (control pressure) to 77± 3 mmHg in group B. In group A, dAA was significantly lower (17.2 ±0.3 μm) at control pressure than at the lower pressure limit of RBF autoregulation (20.3 ± 0.03 μm) (P 0.005). In group B, dAA was 17.3 ± 0.3 μm at control pressure and 17.1±0.4 μm at the intermediate pressure (89 ± 3 mmHg) (P > 0.10). The results indicate that dilation of the afferent arterioles occurs only in the lower part of the autoregulatory pressure range. Possibly, RBF autoregulation at minor pressure reductions is achieved by dilation of the interlobular artery. Participation of the glomerular hilar branches of the afferent arterioles in RBF autoregulation cannot be excluded.
Negative feedback regulation of intracellular Ca2+ and the slope of the dose‐response curve
Authors: BÁRÁNY E.
Published: December 2008

Cytosolic calcium ions are known to act as an intracellular messenger. The response of the cell may be governed by a power of the internal Ca2+ concentration. This causes a very steep relationship between concentration and response. Dose‐response curves of tissues acted on by external agonists are less steep. A possible explanation for this discrepancy is offered. During steady stimulation, which increases Ca2+ inflow and its cytosolic concentration, mechanisms which counteract the increased level by removing Ca2+ are likely to be activated. If these were stimulated by cytosolic Ca2+, they would constitute a negative feedback. If the removal mechanisms were governed by a power of the cytosolic Ca2+ concentration, the negative feedback would have positive cooperativity. A mathematical model is developed where entry of extracellular Caz+ results from stimulation while a cooperative extrusion pump provides negative feedback. It is shown that, in the steady state, positive cooperativity in the extrusion pump is able to reduce the steepness of the dose‐response curve.
Analysis of the inotropic effect of prenalterol in papillary muscles from guinea‐pig hearts
Authors: WOHLFART B. , KHAN A. R.
Published: December 2008

The inotropic effects of prenalterol were studied in papillary muscles isolated from the right ventricle of guinea‐pig hearts. Force production and action potential were recorded. The preparations were paced at 0.4 Hz (at 31–32 °C) under isometric conditions. Prenalterol, in concentration 0.1 μM did not change the action potential duration whereas the peak force and the maximum rate of force development increased by 40.3 and 36.3%, respectively. Time to peak force was slightly shortened (‐3.0%) and so was the time from peak force to half relaxation (‐5.2%). A predetermined stimulus protocol was used for assessment of the recirculation fraction of activator calcium. At selected times an extra contraction was introduced in order to obtain contractile potentiation. Force of the subsequent two test contractions (after fixed intervals) was analysed. Prenalterol slightly reduced the decay of the postextrasystolic potentiation measured in the two test contractions. It is suggested that the inotropic effect of prenalterol is due to an intensified calcium influx during the action potential, and to some extent to more efficient re‐utilization of released calcium. There seems to be a more rapid release of calcium from troponin C giving rise to a shortened time to peak force and an enhanced relaxation.
Bleeding inhibits vagally induced duodenal HCO3‐secretion via activation of the splanchnic nerves in anaesthetized rats
Authors: JÖNSON C. , FÄNDRIKS L.
Published: December 2008

This study was performed on chloralosed rats in order to examine the influence of a minor blood loss on duodenal HCO3‐ secretion. The HCO3‐ output was measured by in situ titration in a duodenal segment. Blood loss of 0.3 ml per 100 g body wt (approximately 5% of total blood volume) and 0.6 ml per 100 g body wt (approximately 10% of total body volume) reduced duodenal HCO3‐ secretion by about 18 and 31%, respectively. Adrenal ligation increased basal output of HCO3‐ but did not affect the bleeding‐induced response. Thoracic epidural anaesthesia or splanchnicotomy did not affect the basal secretion but markedly reduced the depression of duodenal HCO3‐secretion due to blood loss. Vagotomy lowered basal duodenal HCO3‐ secretion and blood loss did not reduce alkaline output in these animals. However, electric stimulation of the cut vagal nerves raised the duodenal HCO3‐ secretion to a similar level as in rats with intact vagal nerves. In this group blood loss reduced the duodenal HCO3‐ output as in rats with intact nerves. It is suggested that a small blood loss, via an activation of the sympathetic nervous system, reduces the vagally controlled part of the duodenal HCO3‐ secretion and that this effect is conveyed in the splanchnic nerves.
Response properties of neurones in the rat olfactory bulb to various parameters of odour stimulation
Authors: DØVING K. B.
Published: December 2008

Carbon fibre filled microelectrodes were used for extracellular recording of spikes discharges from 345 neurones of the lateral aspect of the left olfactory bulb of the rat under pentobarbitone anaesthesia. The identity of the neurones was determined by antidromic activation of the cell axons by electrical stimuli applied to the lateral olfactory tract (LOT) using collision blocking and twin stimuli. The bulbar units were classified as mitral (269) or tufted (16) cells; units in a third class were not identified (60). Application of stimuli (21) was made over a period of 15 s while slowly increasing the odorant concentration monitored by a flame ionization device (FID). The stimulating efficiency reached a maximum at a nasal flow of about 8 cm3 s‐1. The response type excitation was seen in 10.0% and inhibition in 11.8% of the 7245 odour presentations. Each response type was subdivided into four classes according to the reactions to ramp stimulation. In the majority of cases the spike discharge remained constant or followed the odour concentration for the entire stimulation period. In 18% of the cases, the response adapted quickly towards the spontaneous activity level.
Regenerating skeletal muscle cells express insulin‐like growth factor I
Authors: JENNISCHE E. , HANSSON H.‐A.
Published: December 2008

The expression of the trophic peptide insulin‐like growth factor I (IGF‐I; somatomedin C) was investigated in the regenerating soleus muscle of mice after injury by the snake venom taipoxin. No specific IGF‐I immunoreactivity was observed in muscle cells during control conditions. Within 2 days after taipoxin injection, IGF‐I immunoreactivity could be demonstrated in activated satellite cells. Myoblasts and myotubes expressed high IGF‐I immunoreactivity. The IGF‐I immunoreactivity was strictly cyto‐plasmatic and obviously associated with polyribosomes. No vesicular or membraneous IGF‐I immunoreactivity could be demonstrated. It is concluded that IGF‐I is synthesized in myogenic cells during skeletal muscle regeneration. It is suggested that IGF‐I exerts its effects on skeletal muscle mainly by autocrine mechanisms.
The role of prostanoids in the feline intestinal vascular and central haemodynamic responses to i.v. infusion of live E.coli
Authors: SCHÜTZER K.‐M. , HAGLUND U. , FALK A.
Published: December 2008

The role of prostanoids in the feline intestinal vascular and central haemodynamic responses to i.v. infusion of liveE. coli. Acta Physiol Scand130, 359–366. Received 23 July 1986, accepted 11 February 1987. ISSN 0001–6772. Departments of Surgery, East Hospital, Göteborg, and General Hospital, Malmö, Sweden.

Bacterial infusion in the cat, causing experimental septic shock, induces an early vascular response mainly characterized by pulmonary hypertension and intestinal vasocon‐striction. Prostanoids are held to be important mediators of the pulmonary vascular reaction. This study was performed to explore the involvement of prostanoids in the central haemodynamics and the small intestinal vascular reactions in experimental septic shock. Aortic blood pressure was continuously monitored, as were aortic blood flow, the pressure in a. pulmonalis and the small intestinal venous outflow. All cats (n= 24) were given liveE. coli(1010ml‐1) as a continuous intravenous infusion. One series was pretreated with indomethacin, another with UK‐38,485, a specific thromboxane A, synthetase inhibitor, and a third series served as untreated control. The pulmonary hypertensive response was clearly attenuated in the two pretreated series, in fact abolished in the one given UK‐38,485. The early intestinal vasoconstriction was eliminated in the two pretreated series. Later during bacteraemia, when untreated and indomethacin‐pretreated cats showed intestinal vasoconstriction, UK‐38–485‐pretreated animals kept intestinal blood flow within the preseptic range. These data suggest that in the cat, thromboxane A, is the prostanoid mediating the vascular reactions, not only in the lung but also in the small intestine.
Prevention of ischaemic acute renal failure with superoxide dismutase and sucrose
Authors: BAYATI A. , HELLBERG O. , ODLIND B. , WOLGAST M.
Published: December 2008

Prevention of ischaemic acute renal failure with superoxide dismutase and sucrose. Acta Physiol Scand 130, 367–372. Received 24 September 1986, accepted 10 February 1987. Department of Physiology and Medical Biophysics, University of Uppsala, Sweden.

The preventive effects of intravenously administered superoxide dismutase (SOD) and of SOD combined with sucrose on acute renal failure were investigated in rat kidneys exposed to 45 min of warm ischaemia. Superoxide dismutase (20 mg) given just before primary ischaemia and in the early recirculation phase was found to ameliorate the red cell aggregation in the renal medulla, in particular, in the inner stripe of the outer zone the volume of trapped red cells decreased from 11.2 ± 1.6% in untreated animals to 0.02 ± 0.001%, thus allowing improved restoration of medullary blood flow. This was also accompanied by an expected restoration of the urine osmolality reaching almost 400 mOsmkg‐1 after administration of SOD + sucrose. Superoxide dismutase also restored the capillary macromolecular permeability as evidenced by normalization of plasma to lymph transport of proteins. Micropuncture studies showed that in ischaemically damaged but untreated kidneys the tubules were obstructed and that the proximal tubular pressure rose to such a level that the net driving force for filtration approached zero. This explains the marked decrease in glomerular filtration rate (GFR) from a normal value of about 1 ml min‐1 to 0.01 ± 0.02 ml min‐1. After treatment with SOD the tubules were still largely obstructed, resulting in a depression of the net driving force and a decrease in single nephron glomerular filtration rate (SNGFR) to about 11 nl min‐1, that is, to only 25% of the normal SNGFR. The total filtration was 0.09 ± 0.04 ml min‐1. When sucrose (2 ml of a 12% sucrose‐Ringer solution) was given in addition to SOD, with the aim of preventing cellular swelling, rapid wash‐out of rejected cells and cell debris into the urine was observed. The obstructions were eliminated and the free‐flow proximal tubular pressure was next to normal. The resulting SNGFR was about 30 nl min‐1 and the total filtration 0.29 ± 0.06 ml min‐1.
The dopamine receptor antagonist haloperidol blocks natriuretic but not hypotensive effects of the atrial natriuretic factor
Authors: HANSELL P. , FASCHING A. , SJÖQUIST M. , ANDÉN N.‐E. , ULFENDAHL H. R.
Published: December 2008

The dopamine receptor antagonist haloperidol blocks natriuretic but not hypotensive effects of the atrial natriuretic factor.Acta Physiol Scand130, 401–407. Received 11 December 1986, accepted 10 February 1987. ISSN 0001–6772. Department of Physiology & Medical Biophysics and Department of Pharmacology, Biomedical Centre, University of Uppsala, Sweden.

Studies were performed on anaesthetized male Münich‐Wistar rats to investigate the influence of the dopamine (DA) receptor antagonist haloperidol on the natriuretic response to infusion of a synthetic atrial natriuretic factor. The whole kidney glomerular filtration rate (GFR), urinary excretion of electrolytes, and arterial blood pressure (BP) were therefore measured in groups of animals pretreated with haloperidol or vehicle and given a continuous intravenous infusion of atrial natriuretic peptide (ANP; 28 amino acids). Forty‐five minutes of ANP infusion at 10 μg h‐1kg‐1body wt did not increase GFR (change from 1.14 ± 0.08 to 1.15 ± 0.05 ml min‐1g‐1kidney wt). Sodium excretion (UNaV) increased more than four‐fold from 0.037 ± 0.008 to 0.165 ± 0.070 μmol min‐1g‐1kidney wt (P0.01). Potassium excretion (UKV) increased by 86% (P0.001) and the urine flow rate (V) increased transiently by 63% (P0.05) and did not differ from the control value during the last 15 min of ANP infusion. The urinary sodium concentration (UNa) increased almost three‐fold, while BP decreased by 14%. There was no change in urine osmolality. In animals pretreated with haloperidol (I mg kg‐1body wt), 45 min of ANP infusion did not significantly alter GFR (from 1.10 ± 0.08 to 0.98 ± o.09 ml min‐lg‐1kidney wt). TheUNaVdid not increase significantly (change from 0.026 ± 0.006 to 0.030 ± 0.009 μmolmin‐1g‐lkidney wt). TheUKVwas not elevated by ANF infusion. The urine flow rate was transiently elevated by 45% but was not different from the control during the last 15 min of infusion. BothUNaandUosmremained unchanged, but BP was reduced by 11%. In conclusion, the DA receptor blocking agent haloperidol blunts the natriuretic effect of ANP. This action is probably exerted by inhibiting the postulated tubular effects of ANP through an unknown mechanism, but not the vascular ones, since the hypotensive effect of ANP is unaltered. Atrial natriuretic peptide increases sodium excretion not, mainly, by increasing GFR but by affecting tubular transport processes.
Synthesis and secretion of amylase in the rat parotid gland following autonomic nerve stimulation in vivo
Authors: ASKING B. , GJÖRSTRUP P.
Published: December 2008

Synthesis and secretion of amylase in the rat parotid gland following autonomic nerve stimulation in vivo. Acta Physiol Scand 130, 439–445. Received 10 November 1986, accepted 9 February 1987. ISSN 0001–6772. Department of Physiology and Biophysics, University of Lund, Sweden.

Parasympathetic and sympathetic nerve stimulation in vivo, individually and in combination, was used to study secretion and synthesis of amylase in the rat parotid gland. After 30 min with sympathetic nerve stimulation (3 Hz) a decrease in glandular amylase was seen, which corresponded approximately to the salivary output. On the other hand, after parasympathetic stimulation (10 Hz), chosen to obtain comparable amylase output, there was no decrease in glandular amylase, which points to synthesis during such activation. Experiments with incorportation of [3H]leucine, reflecting amylase synthesis, showed that both types of nerve stimulations increased such uptake in parotid protein. These results indicate that beside sympathetic activity, which is the main stimulus for granular amylase secretion, parasympathetic nerve impulses can evoke considerable amylase secretion because amylase synthesis is stimulated and amylase is rapidly available from a special, possibly non‐granular pool. As expected from previous experiments an augmentation of amylase secretion was found, and the present experiments also indicated an augmentation at the level of synthesis when the two nerves were stimulated at the same time.
The effect of amiloride on biliary HCO‐3secretion in the anaesthetized pig
Authors: GROTMOL T. , BUANES T. , RÆDER M. G.
Published: December 2008

The effect of amiloride on biliary HCO‐3‐secretion in the anaesthetized pig.Acta Physiol Scand130, 447–455. Received 20 October 1986, accepted 23 February 1987. ISSN 0001–6772. Institute for Experimental Medical Research, University of Oslo and Surgical Department, Ullevaal Hospital, Oslo, Norway.

The present study was performed on 29 anaesthetized pigs and shows that the bile acid ursodeoxycholic acid (UDCA) produces a flow of bile rich in HCO‐3compared with taurocholic acid (TCA). The slope relating biliary HCO‐3secretion to bile acid secretion was 0.59 (0.44–0.82) and 0.33 (0.29–0.38) during venous infusion of UDCA and TCA, respectively. We next wanted to evaluate the importance of Na+/H+ion exchange for biliary HCO‐3secretion. High doses of amiloride were employed in order to impair the hepatic Na+/H+ion exchanger. It was reasoned that any reduction in H+efflux through the hepatic Na+/H+ion exchanger involved in causing biliary HCO‐3secretion would be translated into an equimolar fall in biliary HCO‐3secretion. We found that amiloride (2.0 ± 10‐‐4mol l‐1plasma) reduced UDCA‐dependent canalicular HCO‐3secretion by 26 (14–35)% without concurrently reducing bile acid secretion. Amiloride (2.9 ± 10‐‐4mol 1‐‐1plasma) did not significantly reduce secretin‐dependent ductular HCO‐3secretion. In this group of animals amiloride reduced bile acid secretion by 13 (5–22)%. It is concluded that Na+/H+ion exchanger is essential for UDCA‐dependent canalicular HCO‐3secretion, but not for secretin‐dependent ductular HCO‐3secretion.
Endurance, what is it? Muscle morphology after an extremely long distance run
Authors: SJÖSTRÖM M. , FRIDÉN J. , EKBLOM B.
Published: December 2008

Endurance, what is it? Muscle morphology after an extremely long distance run. Acta Physiol Scand 130, 513–520. Received 26 July 1984, revised 4 January 1987, accepted 16 February 1987. ISSN 0001–6772. Department of Neurology and Anatomy, University of Umeå, and Department of Physiology III, Karolinska Institute, Stockholm, Sweden.

Biopsies of m. vastus lateralis of a well‐trained 46‐year‐old man were analysed before and after an extremely long distance run (3529 km in 7 weeks). After the period of running, both a decrease of fibre size and a neuromuscular pathology were found. Muscle fibre degeneration and regeneration, especially of type 2 (fast‐twitch) fibres, was seen as well as signs of damage to the peripheral nerves. The relative amount of type I (slow‐twitch) fibres was higher after the run. The relationships between light and electron microscopical characteristics normally present could not be found in the specimens of this man. The changes in fibre size as well as the other microscopical characteristics may express an adaptation through more or less complete fibre transformation. However, we could not rule out that a selective elimination of fibres also contributed to the observed changes. In that case, the underlying pathophysiology might have been a peripheral arterial insufficiency which was related to the extreme functional demands. These disturbances may have affected type 2 fibres more than type I fibres. Endurance may, on this basis, express an adaptation of the muscle through elimination of weak fibres, that is, fibres related to limited functional capacities.
Binding and degradation of vasoactive intestinal peptide in prolactin‐producing cultured rat pituitary tumour cells (GH4C1)
Authors: BJøRO T. , WIIK P. , OPSTAD P. K. , GAUTVIK K. M. , HAUG E.
Published: December 2008

Binding and degradation of vasoactive intestinal peptide in prolactin‐producing cultured rat pituitary tumour cells (GH4C1). Acta Physiol Scand 130, 609–618. Received 17 October 1986, accepted 2 March 1987. ISSN 0001–6772. Hormone Laboratory, Aker Hospital, Oslo, Norwegian Defence Research Institute, Division for Environmental Toxicology, Kjeller, and Institute of Medical Biochemistry, University of Oslo, Norway.

Vasoactive intestinal peptide (VIP) stimulates prolactin (PRL) secretion from cultured rat pituitary cells (GH cells) (Bjero et al. 1984). This study demonstrates the presence of specific receptors for 125I‐VIP on the GH4C1 cells. Specific binding was rapid and biphasic giving a transient plateau lasting from 7 to 30 min. Thereafter specific binding declined to about one‐third after 90 min. This coincided with enhanced degradation of 125I‐VIP. The degradation was mainly cell‐mediated and only partly receptor dependent. Trichloroacetic acid precipitation and absorption chromatography indicated that the degradation products were either 125I‐ and/or small labelled peptide fragments. Bioassay, RIA and rebinding studies also demonstrated degradation of VIP. Pretreatment of GH4C1 cells with trypsin decreased the rate of degradation of 125I‐VIP, but also reduced the amount of specific binding. Scatchard analysis of binding data indicated the existence of two independent classes of receptors, one with Kd= 2.2 nM and Bmax= 15 fmol per 106 cells and another with Kd= 180nM and Bmax= 550 fmol per 106 cells. The IC50 for VIP, PHI and secretin were 4, 5 and 500 nM, respectively. We conclude that the high affinity receptor is the most probable mediator of VIP on PRL secretion. The effect of VIP and PHI on PRL secretion in GH4C1 cells is mediated through one common receptor.
Mechanical, morphological and pharmacological properties of oesophageal varices and small mesenteric veins in portal hypertensive rabbits
Authors: JENSEN L. S. , JUHL C. O. , MULVANY M. J.
Published: December 2008

Mechanical, morphological and pharmacological properties of oesophageal varices and small mesenteric veins in portal hypertensive rabbits. Acta Physiol Scand 130, 649–656.

The properties of isolated small oesophageal and mesenteric veins were investigated in a rabbit model subjected to a 4–week period of portal vein stenosis. The animals developed oesophageal varices and these together with the small mesenteric veins were mounted on a myograph. Compared with sham‐operated controls portal hypertension resulted in an increased normalized inner radius and media thickness of the oesophageal veins resulting in a non‐significant increase in the media to lumen ratio, while the inner radius decreased as media thickness increased in mesenteric veins resulting in a significant (P 0.01) increase in the media to lumen ratio. When activated, the active wall tension of both the oesophageal and mesenteric veins was increased following portal hypertension, but the active media stress was unchanged. The EC50 for noradrenaline and angiotensin I1 did not change in portal hypertensive vessels compared with controls and was equal in oesophageal and mesenteric vessels. The ability of isoprenaline and serotonin to relax pre‐contracted vessels of both types was reduced by the portal hypertension. The results of these studies suggest that the development of oesophageal varices is not only due to increased portal venous pressure.
Sprinters and marathon runners. Does is kinetic knee extensor performance reflect muscle size and structure?
Authors: JOHANSSON C. , LORENTZON R. , SJÖSTRÖM M. , FAGERLUND M. , FUGL‐MEYER A. R.
Published: December 2008

Sprinters and marathon runners. Does isokinetic knee extensor performance reflect muscle size and structure?Acta Physiol Scand130, 663–669.

In order to evaluate relationships between structure and concentric function of the quadriceps muscle, isokinetic maximum knee extensor output at different velocities of angular motion (30–180 degrees s‐1), integrated electromyographic activity (iEMG), cross‐sectional area (CSA) of m. quadriceps and fibre composition of m. vastus lateralis were analysed in five sprinters and five marathon runners (all males). Both output and input parameters, concerning peak torque (PT), instantaneous power (IP), contractional work (CW) and the summed iEMG were closely correlated to the m. quadriceps CSA, as well as to the calculated absolute type II (A + B), IIA and IIB fibre areas of m. vastus lateralis. When PT, IP, CW and the summed iEMG were corrected for CSA, such relationships were found only at 180 degrees s‐1 and only for type IIA fibre area. The electromyographic findings indicate that m. vastus lateralis was representative for the total mechanical output. The calculated mean power output (CW s‐1) and output/input balance (CW/iEMG) describe similar relationships with the velocity of angular motion and were not related to the CSA or to the absolute area of any fibre type. The calculated optimal CW per second and CW/EMG occur for sprinters at about 450 degrees s‐1 and for marathon runners at about 270 degrees s‐1, that is, velocities well above the capacity of the isokinetic dynamometer. Our observations indicate that the peak torque or instantaneous power, during single maximum knee extensions, at least at 180 degrees s‐1, express characteristics of the muscle structure.
Effects of intraventricular injections of galanin on neuroendocrine functions in the male rat. Possible involvement of hypothalamic catecholamine neuronal systems
Authors: MELANDER T. , FUXE K. , HÄRFSTRAND A. , ENEROTH P. , HÖKFELT T.
Published: December 2008

Galanin–catecholamine interactions have been analysed within the hypothalamus and the anteromedial frontal cortex of male rats by means of quantitative histofluorimetrical and biochemical measurements of catecholamine fluorescence in discrete catecholamine nerve terminal systems and measurements of serum levels of adenohypophyseal hormones and corticosterone using radio‐immunoassay determinations. 125I‐galanin binding sites were analysed and related to the distribution of galanin‐immunoreactive neuronal structures in the median eminence and paraventricular hypothalamic nucleus. The results show that intraventricular injections of galanin in the awake and unrestrained male rat produce rapid increases of prolactin and growth hormone secretion but no effects on serum luteinizing hormone, thyroid stimulating hormone or on corticosterone levels. These changes in neuroendocrine function were associated with a selective reduction of the catecholamine stores in the medial palisade zone of the median eminence at the 20 min time interval. 125I‐galanin binding sites were found throughout the hypothalamus including the median eminence and the magnocellular part of the paraventricular hypothalamic nucleus with a good correspondence with galanin immunoreactivity. It is suggested that the enhancement of prolactin secretion induced by galanin involves an interaction between galanin and dopamine in the medial palisade zone leading to a reduced synthesis and/or release of dopamine and thus to a reduced prolactin inhibitory activity and to increases in prolactin secretion. A possible involvement of hypothalamic catecholamines in the galanin‐induced changes of growth hormone secretion remains to be established.
Appropriate and inappropriate hypothalamic cold thermosensitivity in Willow Ptarmigan
Authors: MERCER J. B. , SIMON E.
Published: December 2008

Hypothalamic thermosensitivity has been investigated in conscious Willow Ptarmigan (Lagopus lagopus lagopus) provided with chronically implanted hypothalamic perfusion thermodes. The birds were exposed to either cold (Ta‐10°C) or warm (Ta+ 25°C) ambient conditions while hypothalamic temperature (Thy) was clamped for periods of 20 min at different set levels between 28°C and 43°C. The responses of the animals to hypothalamic thermal stimulation were classified by comparing them with those normally found in mammals. At Ta– 10°C hypothalamic heating inhibited ongoing shivering, causing a fall in body‐core temperature (Tc) (appropriate mammalian‐like response). Strong levels of hypothalamic cooling (Thy < 34.0°C) also caused a fall in Tc due to inhibition of shivering (inappropriate mammalian‐like response). However, weaker levels of hypothalamic cooling (Thy 34–36°C), facilitated ongoing shivering, resulting in small increases in Tc (appropriate mammalian‐like response). At Ta+25°C hypothalamic heating facilitated ongoing panting while weak (Thy 38°C) levels of hypothalamic cooling inhibited ongoing panting (both mammalian‐like responses). The observation of a weak mammalian‐like cold hypothalamic thermosensitivity in Willow Ptarmigan indicates that these birds possess some specific cold thermosensors in the hypothalamic region. This finding suggests that hypothalamic temperature dependence in birds and mammals is fundamentally similar.
Mechanical jumping power in young athletes
Authors: VIITASALO J. T. , ÖSTERBACK L. , ALEN M. , RAHKILA P. , HAVAS E.
Published: December 2008

Mechanical jumping power was determined for 286 young male athletes representing six sports events and ranging in calendar and skeletal ages from 8.8 to 17.1 and from 7.8 to 18.1 years, respectively. The subjects performed successive maximal vertical jumps on a contact mat for 30 s. The number of jumps and their cumulative flight time after 15 and 30 s were used for calculations of mechanical power. The jumping performances of the young athletes were found to be reproducible from the age of 10–12 years in respect to the angular displacement of the knee and duration of contact. Absolute mechanical power, as well as power related to body weight, increased with calender and skeletal ages. Of the anthropometric characteristics, the circumference of the thigh and body weight showed the highest correlation with mechanical power; subjects with the greatest thigh circumference and body weight having the lowest mechanical power. The subjects were divided into ‘power’ (track and field, gymnastics) and ‘endurance’ (skiing, orienteering) groups. The former reached higher mechanical power values than the latter. Mechanical power for the second 15‐s jumping period was on average 4.7% lower than for the first. The events did not differ from each other in respect of the decrease in power.
Respiratory modulation of shivering intensity in the pigeon
Authors: HOHTOLA E. , JOHANSEN K.
Published: December 2008

Respiration and shivering were measured in unanaesthetized, cold‐exposed pigeons using pneumotachography and electromyography, respectively. The instantaneous intensity of shivering in the pectoral muscle varied in phase with respiration. Power spectral analysis showed that the main frequency components of respiration and demodulated EMG coincided exactly. The intensity of shivering was highest during end‐expiration and lowest at end‐inspiration. This was confirmed by cross‐correlation analysis of respiration and demodulated EMG. The absolute level of modulation remained constant (c. 10 μV peak‐to‐peak) despite changes in the general intensity of shivering. On the other hand, the relative depth of modulation was highest during incipient shivering. These facts indicate that only a part of the motor units recruited for shivering is susceptible to respiratory modulation and that this part is first recruited during incipient shivering. Inhalation of 5% CO2 did not affect the interaction between respiration and shivering although respiration frequency varied from 25 to 6o min‐1. Thus, pulmonary chemoreceptors do not mediate this effect. It is suggested that the interaction between respiration and shivering occurs directly in the CNS. The question whether the interaction is adaptive for the animal or merely reflects a common evolutionary history of the underlying neural circuits is discussed.
Central venous pressure – a physiological stimulus for secretion of atrial natriuretic peptide in humans?
Authors: SCHÜTTEN H. J. , JOHANNESSEN A. C. , TORP‐PEDERSEN C. , SANDER‐JENSEN K. , BIE P. , WARBERG J.
Published: December 2008

A sensitive radio‐immunoassay (RIA) for the measurement of human α‐atrial natriuretic peptide (ANP) in extracted plasma was developed and used in a study of the possible effect of posture on the concentration of ANP in plasma. The least detectable quantity was less than 2 pg per tube equivalent to 5 pg ml‐1 plasma. In the middle sensitivity range (approximately 50 pg per tube), the within‐assay and between‐assay coefficients of variation were 4.0 and 2.8%, respectively. The recovery of ANP added to plasma prior to extraction was 95–101%. High pressure liquid chromatography (HPLC) of plasma extracts revealed that endogeneous ANP was eluted in the same fractions as synthetic ANP. In order to investigate the effect of posture on the concentration of ANP in plasma six healthy volunteers were exposed to five positions in the following sequence: supine, standing, sitting, supine and 10° head‐down tilt on a tilt‐table. The concentration of ANP was lower in the standing and sitting position than in the supine and head‐down tilted position. In another study six healthy volunteers were subjected to passive tilting on a tilt‐table in order to evaluate the effect of tilting on blood pressure (BP), heart rate, central venous pressure (CVP) and the concentration of ANP in plasma. It was found that a fall in CVP was accompanied by a significant decrease in the concentration of ANP and that a rise in CVP was accompanied by a rapid increase in the concentration of ANP in plasma. The results are in agreement with the hypothesis that CVP is a physiological stimulus for the secretion of ANP.