bluuebunny/crossref_metadata_2025_split huggingface dataset:
Different effects of the ionophore A‐23187 and D‐glucose on 45Ca2+ fluxes in isolated islets of ob/ob‐mice
Authors: Tamarit‐Rodriguez Jorge 
Published: December 2008

AbstractFluxes of 45Ca2+ were studied in β‐cell rich islets of non‐inbred ob/ob‐mice, using LaCl3 to wash out extracellular and superficially bound 45Ca2+. The ionophore A‐23187 (10,μM) increased the 45Ca2+ uptake in islets both at 3 and 20 mM D‐glucose, the effect being more pronounced after 10 min than after 120 min of incubation. In incubations for 120 min, 20 mM D‐glucose induced a higher uptake of 45Ca2+ than did A‐23187. The ionophore enhanced the unidirectional efflux of 45Caa+ from preloaded islets. Pretreatment of islets with 20 mM D‐glucose in non‐radioactive medium inhibited the subsequent D‐glucose‐induced 45Ca2+ uptake. Similar pretreatment with A‐23187 increased the subsequent ionophore‐induced 45Ca2+ uptake. The results suggest that A‐23187 acts by catalyzing Ca2+ fluxes across the β‐cell plasma membrane. The different effects of D‐glucose and A‐23187 on 45Ca2+ fluxes suggest that the two agents act through different mechanisms in the β‐cells.
A modified Sperber technique for direct estimation of true renal tubular excretion fraction
Authors: Odlind Bo 
Published: December 2008

AbstractThe Sperber technique in the hen is particularly suitable for the study of renal tubular secretion. However, results obtained with this technique vary considerably, due to an unpredictable and highly variable shunting of renal portal blood. In an attempt to get a total and stable renal perfusion by portal blood from the leg, appropriate shunt vessels were ligated. This procedure was found to force all portal blood from the leg to perfuse the ligated kidney, without affecting the symmetry of glomerular filtration or renal clearance of 125‐I‐Na‐o‐iodohippurate between the kidneys. In conclusion, the abolition of renal portal shunt flow allows use of the Sperber technique for a direct estimation of the true tubular excretion fraction (TTEF) of a substance. Thus, TTEFPAH, a measure of the tubular excretion efficiency of para‐amino‐hippuric acid, was found to be about 70%. The stable renal perfusion in ligated animals will also facilitate comparative studies of renal tubular excretion in the hen. Moreover, no animal has to be rejected due to a low renal perfusion of portal blood. Furthermore, the use of ligated hens makes it unnecessary to use markers for the renal perfusion of portal blood when steady‐state experiments are performed. Finally, the total renal perfusion of portal blood in ligated animals will facilitate the demonstration of a secretory component in the renal handling of substances with a low affinity for the renal transport system.
Glycogen depletion of different fibre types in human skeletal muscle during intermittent and continuous exercise
Authors: Essén Birgitta 
Published: December 2008

AbstractMuscle biopsies from the vastus lateralis were obtained from thirteen healthy subjects at rest and at intervals during continuous and intermittent exercise. After freeze‐drying of the muscle sample, fragments of single fibres were dissected out and stained for myofibrillar ATPase with preincubation at pH 10.3, 4.6 or 4.3 to identify type 1, II A and II B fibres respectively. The remaining part of each fragment was used for quantitative glycogen analyses. At rest, mean glycogen content was significantly higher in type II fibres (402 mmol/kg dry weight) than in type 1 (344 mmol/kg dry weight). After 60 min continuous exercise at moderate work load a more pronounced glycogen depletion had occurred in type I (277 mmol/kg dry weight) than in type II (A‐r B) fibres (113 mmol/kg dry weight). With 60 min intense intermittent exercise a significant and similar depletion occurred in both type I (213 mmol/kg dry weight) and type II (A + B) fibres (203 mmol/kg dry weight). With continuous intense exercise to exhaustion (4–6 min), glycogen depletion was more marked in type II (A‐ B) (1 !8 mmol/kg dry weight) than type I fibres (74 mmol/kg dry weight). These data imply that the glycogen depletion pattern in muscle fibres is determined mainly by the work intensity but the lower glycogen depletion per unit time in intermittent compared with continuous intense exercise indicates that the mode and duration of exercise is important, too.
A study of permanent adipsia induced by medial forebrain lesions
Authors: Rundgren Mats , Fyhrquist Frej 
Published: December 2008

AbstractCerebral lesions involving most of the anterior wall of the third ventricle, and the medial part of the septal region, induced a permanent loss of thirst in two goats. The ventral part of the lamina terminalis remained intact in one of the animals. Pronounced dehydration (10–13% loss of b.wt.) developed during periods (3–7 days) when water supplementation was omitted. Determinations of plasma arginine vasopressin in one of the animals revealed that the dehydration did not cause any significant increase in the secretion of antidiuretic hormone. However, the water deficit induced a considerable rise in plasma renin activity and tachycardia. If anything, the carotid blood pressure became slightly elevated towards the end of 7 d dehydration periods. The lesions obviously inactivated a cerebral sensory mechanism controlling water balance. It may have been due mainly to destruction of juxtaventricular receptors in the anterior hypothalamic region, but perhaps also to a disruption of afferents from such receptors located posterior to this cerebral level.
Efferent innervation of the small intestine by adrenergic neurons from the cervical sympathetic and stellate ganglia, studied by retrograde transport of peroxidase
Authors: Lundberg Jan M. , Dahlström A. , Larsson I. , Pettersson G. , Ahlman H. , Kewenter J. 
Published: December 2008

AbstractThe nervous pathways between the small intestine of cat and guinea pig and various sympathetic ganglia were investigated by the retrograde horse‐radish peroxidase (HRP) technique. HRP was injected at multiple sites in the wall of the duodenum and the first third of the jejunum. At 1–5 days after (he injections. the HRP reaction product was searched for in various sympathetic ganglia. Not only the coeliac and nodose ganglia, but also the superior cervical, medial cervical, stellate and thoracic ganglia contained HRP‐positive nerve cells. Crushing the cervical vagal nerve prevented the occurrence of HRP‐reaction in the cervical ganglia, indicating that the HRP was transported from the gut to the cervical ganglia bia axons in the vagal nerve. The results demonstrate that the sympathetic ganglia in the neck (sup. and med. cerv. ganglia and stellate ggl.) send efferent fibres to the small intestine.
Triton detergents and the frog neuromuscular end‐plate: An electrophysiological and ultrastructural study
Authors: Rydqvist Bo 
Published: December 2008

AbstractThe effects of the nonionic detergents Triton X‐45 and Triton X‐100 were studied in the frog muscle end‐plate, by intracellular recordings of spontaneous miniature end‐plate potentials (m.e.p.p.'s) and the potential changes produced by iontophoretic application of acetylcholine (ACh‐potentials). In addition, the ultra‐structural changes produced by Triton X‐100 were studied by transmission electron microscopic and freeze‐fracture techniques. It was found that Triton X‐45 and Triton X‐100 caused a rapidly developing reduction of the amplitude of the m.e.p.p.'s. The response lo iontophoretic application of acetylcholine was reduced by Triton X‐100. Following return to normal Ringer solution the ACh‐potentials recovered, although not completely. The dissociation constant calculated from the rate constants for onset and offset of the reaction (KD= k2/kl) was 5–50 μM depending on the type of stoichiometric reaction presumed to occur between Triton X‐100 and the cholinergic receptor. The ultrastructural changes observed indicate that the nerve terminal plasma membrane and mitochondria are affected by Triton X‐100. Leakage of Ca2+from the latter may therefore be the cause of the increase in m.e.p.p. frequency. It is concluded that the influence on the amplitude of the m.e.p.p.'s and the ACh‐potentials can be attributed to a direct effect of the detergent upon the acetylcholine receptor protein.
Influence of intravenously administered catecholamines on cerebral oxygen consumption and blood flow in the rat
Authors: Berntman Leif , Dahlgren Nils , Siesjö Bo K. 
Published: December 2008

AbstractIn order to study effects of catecholamines on cerebral oxygen consumption (CMRo2) and blood flow (CBF), rats maintained on 75 % N2O and 25 % O2, were infused i.v. with noradrenaline (2, 5, or 8 μpg. kg‐1. min‐1) or adrenaline (2 or 8, μg. kg‐1.min‐1) for 10 min before CBF and CMRozwere measured. In about 50% of animals infused with 2–8,μg. kg‐1min‐1of noradrenaline, CMRoz(and CBF) rose. However, there was no dose‐dependent response, and CMRo2, did not exceed 150% of control. The effects of noradrenaline in a dose of 5 μg. kg‐l. min‐1on CMRo2, and CBF were blocked by propranolol (2.5μg.kg‐1). In animals infused with adrenaline (8 μg.kg‐1.min‐1) CMRo2, was doubled and, in many, CBF rose 4‐ to 6‐fold. It is concluded that, when given in sufficient amounts, catecholamines have pronounced effects on cerebral metabolism and blood flow, the effects of adrenaline on CMRo2, and CBF resembling those observed in status epilepticus.
The effect of vigorous physical activity at work on serum lipids with a special reference to serum high‐density lipoprotein cholesterol
Authors: Lehtonen A. , Viikari J. 
Published: December 2008

AbstractSerum lipid concentrations of lumberjacks whose occupational physical activity is most vigorous were compared with those of electricians. The lumberjacks had significantly higher serum HDL‐cholesterol and significantly lower triglyceride and free fatty acid concentrations hut there were no significant differences in total cholesterol levels. The favourable effect of vigorous physical activity at work on lipid metabolism is, however, epidemiologically not seen, obviously due to negative risk factors in lumberjacks' life.
Isometric and dynamic endurance as a function of age and skeletal muscle characteristics
Authors: Larsson Lars , Karlsson Jan 
Published: December 2008

AbstractThe aim of the study was to investigate the influence of age on endurance of human skeletal muscle. An attempt was made to correlate muscular performance at various ages with some morphological and enzymatic characteristics of the muscle. Fifty healthy men, 22–65 years of age, with low daily physical activity (clerks) volunteered for the study. Isometric and dynamic endurance were determined under standardized conditions and measured in relation to maximum strength, thereby correcting for individual as well as age differences in maximum strength. Biopsies taken from the quadriceps muscle were used for muscle fibre classification, fibre area determinations, and measurements of some enzyme activities (Mg2+‐ stimulated ATPase, myokinase (MK), lactate dehydrogenase (LDH), LDH isozymes). Maximum isometric and dynamic strength decreased in the older groups while no significant change was seen in isometric or dynamic endurance. Significant correlations were observed between endurance and fibre type distribution, fibre areas, and LDH isozyme activities.
Hepatic triacylglycerol and fatty‐acid biosynthesis during hypoxia in vivo
Authors: Kinnula Vuokko L. , Savolainen Markku J. , Hassinen Ilmo 
Published: December 2008

AbstractHepatic fatty acid biosynthesis and the activity of phosphatidate phosphohydrolase, the rate‐limiting enzyme of triacylglycerol biosynthesis, were studied after hypoxic periods of 1 and 7 days under hypo‐bark conditions at 40.8 kPa. Phosphatidate phosphohydrolase activity increased 2‐fold in the soluble fraction of the liver after one day at 40.8 kPa, but had returned to normal by 7 days. This was accompanied by a significant increase in liver triacylglycerol and sn‐glycerol‐3‐phosphate. The phosphatidate phosphohydrolase activity increased continuously over 7 days in the pair‐fed controls, probably due to the restriction on food. Measured as in vivo incorporation of 3H2O into lipids, the hepatic fatty acid synthesis rate increased somewhat in acute hypoxia, but returned to normal values during 7 days of hypoxia. Plasma free fatty acids increased markedly after 24 h in the fasting controls (90 %) with a smaller increase in the hypoxic group (50%) due to peripheral lipolysis. Hepatic glycogen stores decreased in the hypoxic and fasting animals both after 1 and 7 days. It Is concluded that hypoxia induces the accumulation of fat into the liver at least partly as a consequence of an increase in phosphatidate phosphohydrolase activity in the soluble fraction of the liver.
Suppression of autonomic postganglionic discharges by pentobarbital in dogs, with or without endotoxemia
Authors: Halinen M. O. , Hakumäki M. O. K. , Sarajas H. S. S. 
Published: December 2008

AbstractInitial effects of pentobarbital (8 mg/kg) on autonomic efferent and afferent discharge rates were studied in 26 dogs under morphine‐chloralose anesthesia. Half of the dogs were given endotoxinE. coli(1 mg/kg) before pentobarbital. The postganglionic cervical vagal efferentation of all the dogs decreased as did the postganglionic cardiac sympathetic efferentation. The heart rate of the dogs given endotoxin decreased, while an increase in heart rate with abolition of respiratory arrhythmia, was observed in dogs without endotoxin. The aortic pressure of the former dogs dropped while it fell only slightly in the latter ones. The aortic arch baroreceptor activity decreased while the changes of left atrial B‐type receptor activity were not significant. The changes of the left atrial and central venous pressures were slight hut thosc of the pulmonary arterial pressure generally paralleled the changes in the aortic pressure. Pentobarbital, accordingly, seems to exert both sympatholytic and vagolytic effects. These explain the heart rate changes, as well as the impaired cardiac contractility it evokes. The obvious impairment of cardiovascular control mechanisms by pentobarbital should be seriously considered in investigations into the cardiovascular control.
Effect of lowering of the temperature on the tissue levels of cAMP, cGMP, PGE and PGF2β, in spontaneously beating rat atria preparation
Authors: Parantainen J. , Metsä‐Ketelä T. , Vapaatalo H. 
Published: December 2008

AbstractTissue levels of cAMP, cGMP, PGE, and PGF2βwere measured in spontaneously beating rat atria preparation at 20°C and 37°C. At 20°C the formation of cAMP increased in correlation with the markedly increased amplitude and reduced frequency. The other biochemical parameters were not significantly affected by the low temperature.
Effects on fluid balance induced by non‐febrile intracerebroventricular infusions of PGE2, PGFZ2β, and arachidonic acid in the goat
Authors: Leksell L. G. 
Published: December 2008

AbstractProstaglandins (PG) E2, F2α(30 ng/kg.min‐1) and arachidonic acid (150 and 300 ng/kg.min‐1) were infused for 30 min into the lateral cerebral ventricle of conscious hydrated and non‐hydrated goats. Like previously shown as concerns PGE1. PGE2was found to inhibit the water diuresis and cause some increase in the renal sodium excretion in the hydrated animal, and to elicit thirst in the non‐hydrated goat. The effects of PGE2were enhanced when hypertonic (0.25 M) NaCl was simultaneously infused into the ventricle. The antidiuretic effect of PGF2α, was less pronounced, and drinking only occasionally occurred when this PG was infused into the non‐hydrated animal. Only a weak, post‐infusion reduction of the water diuresis was observed when arachidonic acid was administered into the hydrated goat. Neither the PG:s, nor arachidonic acid affected the temperature regutation of the animals. The possibility is discussed that the lack of febrile response was due to the choice of platinum‐iridium as material for the cerebral irnplantations. It is suggested that PGE, might have interacted with CSF Na+in stimulating juxtaventricular receptors involved in the control of fluid balance. The experiments do not support the concept that PG:s of the E series constitute a cerebral humoral link in pyrogen‐induced fever.
The effects of ureteral occlusion and renal venous constriction on kidney kallikrein‐kinin and prostaglandin systems in dogs
Authors: Olsen Uffe Bang 
Published: December 2008

AbstractOlsen, U. B. The effects of ureteral occlusion and venal cenous constriction on kidney kallikrein‐kinin and prostaglandin systems in dogs. Acta physiol. scand. 1978. 104. 443–452.The intrarenal pressure was raised to 40–50 mmHg by ureteral occlusion or by renal venous constriction in anesthetized dogs loaded with 10% mannitol in saline and with a urine flow of approximately I ml/min/ kidney. Both manoeuvres produced vasodilation and decreased urine creatinine excretion (GFR). Ureteral occlusion was associated with a marked antinatriuresis, which contrasted the variable decrements in sodium excretion during renal venous constriction. Ureteral occlusion did not affect urine excretion of kallikrein or kinins, whilst renal venous constriction decreased urinary kallikrein excretion, yet markedly increased urinary kinin excretion. Ureteral occlusion and renal venous constriction comparably increased urine prostaglandin (E‐like) excretion by a presumably pressure dependent mechanism. Inhibition of prostaglandin synthesis by indomethacin abolished the vasodilation during renal venous constriction and this was accompanied by marked reductions of urinary creatinine (GFR) and kallikrein excretions. whilst the kinin excretion was enhanced as observed before the administration of indomethacin.
Phosphorylation of endogenous proteins by endogenous protein kinase of density gradient—purified plasma membrane vesicles of Ehrlich cells
Authors: Ronquist Gunnar , ÂGren Gunnar , Lindqvist Inger 
Published: December 2008

AbstractA phosphorylation of endogenous acceptor protein(s) has been demonstrated to occur in membraneous vesicles prepared from Ehrlich ascites tumour cells. The reaction was catalyzed by endogenous protein kinase in the présence of exogenous (γ32P)ATP. A considérable increase of the spécifie protein kinase activity took place when the plasma membrane préparation was subjected to a further gradient centrifuga‐tion in Dextran T 150. This was done in the présence of a slightly alkaline phosphate buffer containing Mg‐ions which resulted in the formation of a well defined vesicular préparation at density 1.035 in the gradient. The apparent Km and Vmax for the reaction with vesicles and exogenous (γ32P)ATP were deter‐mined and found to be 0.022 mM and 0.23 nmol × mg‐1× 10 min‐1, respectively. Neither cyclic AMP nor cyclic GMP did stimulate the protein kinase‐catalyzed reaction. Instead, a clear inhibition of the reaction by the cyclic nucleotides was unexpectedly registered. Adenosine at 0.5 mM also inhibited the reaction. Calcium ions were inhibitory at ail concentrations tested in the présence of a fixed (γ32P)ATP/Mg2+ ratio. When Mg‐ions were stoichiometrically replaced by Ca‐ions practically no activity was observed.
Progesterone effects on the evolution of myometrial activity in vivo in the non‐pregnant rabbit
Authors: BATRA S. , ÅKERLUND M. , LAUDANSKI T. 
Published: December 2008

AbstractIn order to study the influence of progesterone on the myometrial activity ovarian secretion of progesterone was stimulated by intravenous injection of human chorion gonadotrophin (HCG, 75 IU) in 9 nonpregnant rabbits. 4 rabbits, used as controls, were given only saline. Plasma progesterone concentration in blood samples taken at frequent intervals (2–4 h) during the recording was measured by radioimmunoassay. In the controls, the myometrial activity and the plasma levels of progesterone did not change. After 1 h of HCG administration the amplitude of contraction began to decrease and the frequency began to increase after 3 h. After about 5 h the changes in amplitude and frequency were generally fully developed. This pattern of myometrial activity persisted throughout the recording period (12 h) and was also present in recordings made after 24 and 48 h of HCG injection. A maximal increase in plasma progesterone concentration (5.0 ng/ml) had already occurred by 2 h after the HCG injection and gradually decreased thereafter. It is concluded that an elevation in the level of progesterone in non‐pregnant rabbits resulting from increased ovarian output (through HCG) has a pronounced and immediate depressing effect on the character of myometrial activity which is indicative of a shift from nonpregnant to pregnant type.
Effects of indomethacin on regional blood flow in conscious rabbits—a microsphere study
Authors: BILL ANDERS 
Published: December 2008

AbstractIn an attempt to reveal the importance of prostaglandins in the control of regional blood flow 20 mg/kg b.wt. indomethacin was giveni.v.in conscious resting rabbits. Regional blood flow determinations were made before and 20 min after the injection using the labelled microsphere technique. The blood flow in the stomach wall was reduced by 0.75 ± 0.17 g·min‐1·g‐1from a level of 1.64 ± 0.24 g·min‐1·g‐1. In jejunum the corresponding figures were 0.44 ± 0.12 and 1.26 ± 0.17 and in the brain 0.29 ± 0.10 and 1.24 ± 0.10. The blood flow in the liver via the hepatic artery increased by 0.20 ± 0.02 g·min‐1·g‐1from a level of 0.13 ± 0.02 g·min‐1·g‐1. In the retina there was a reduction in blood flow by 2.75 ± 1.03 mg·min‐1from a starting level of 15.1 ± 2.3 mg·min‐1. In a number of other tissues investigated there were no significant effects of the drug. The results suggest that under resting conditions prostaglandins play a role in the control of blood flow in the gastrointestinal tract, the brain and the retina—tissues which are likely to be rather active under such conditions.
Plasma catecholamines, cyclic AMP and metabolic substrates in hemorrhagic shock of the rat. The effect of adrenal demedullation and 6‐OH‐dopamine treatment
Authors: FREDHOLM BERTIL B. , FARNEBO LARS OVE , HAMBERGER BERTIL 
Published: December 2008

AbstractPlasma catecholamines, cyclic AMP and metabolic substrates in hemorrhagic shock of rats was studied in 4 groups of animals: 1) Control rats, 2) rats with adrenal demedullation, 3) rats with 6‐OH‐dopamine induced chemical sympathectomy, and 4) rats with combined demedullation and sympathectomy. The rats were bled to a systemic blood pressure of 35 mmHg.The basal plasma level of noradrenaline (NA), adrenaline (A) and dopamine (DA) in control animals was each about 1 nmol/1. After hemorrhage for 1 h the A levels had reached 50 nmol/1 and there was little further rise after 4 h. The rise was eliminated by demedullation but unaffected by sympathectomy. NA levels rose continuously in the control and in the sympathectomized rats. At 1 h the level was about 4 nmol/1 and at 4 h about 20 nmol/1. The demedullated rats showed a 3‐fold increase in circulating NA, while little or no change was seen in the combined demedullated and sympathectomized rats. DA levels did not change in any of the groups during the first hour, but were markedly elevated after 4 h of hypotension.Cyclic AMP and glucose levels in plasma showed a rapid increase 1 h after hemorrhage and thereafter returned to or below basal values. Demedullation largely prevented the increase, while sympathectomy had no effect. The increase in lactate and pyruvate levels were diminished but not eliminated by either sympathectomy or demedullation. Glycerol levels were unchanged and FFA decreased in all groups of rats.The results show that the adrenal medulla is the dominating source of plasma catecholamines in hemorrhagic shock in rats. The initial increase in plasma glucose and cyclic AMP appear to be largely mediated by adrenal A. The subsequent fall in these parameters and derangement of circulatory homeostasis are not, in the present shock model, primarily due to a failure of catecholamine secretion, but rather to a decreased responsiveness of peripheral tissues to catecholamine stimulation.