bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Colloid Osmometer for Small Fluid Samples
Authors: Aukland K. , Johnsen H. M. 
Published: December 2008

AbstractA membrane colloid osmometer for measurement on samples down to 5 μl has been developed. Pellucid acryl plastic is used for most parts of the osmometer, allowing visual inspection of the reference fluid chamber. The osmometer base is attached directly to a Hewlett‐Packard pressure transducer, replacing the original dome of the transducer, thereby avoiding extra connections and leakage. The exposed membrane area has a diameter of 3 mm, and the membrane may be changed without completely disassembling the osmometer. With Amicon UM‐10 membranes and 0.9 % saline as reference fluid, the equilibration time for measurements on human sera was 2–4 min. Reduction of equilibration time to about 1 min was obtained by “priming” and flushing the membrane with serum ultrafiltrate. Reproducible measurements were obtained on samples down to 4–5 μl.
Acceleration Stress and Effects of Propranolol on Cardiovascular Responses
Authors: Bjurstedt H. , Rosenhamer G. , Tydén G. 
Published: December 2008

AbstractHeart rate, arterial pressure and cardiac output were recorded in six physically well‐trained, young male volunteers in the sitting position at normal gravity and at 3 G acting in the head‐seat direction, before and after beta‐adrenergic blockade by propranolol. Studies were performed both at rest and during leg exercise at a load corresponding to 50 % of the maximal oxygen uptake. After propranolol, the heart rate response to increased G at rest averaged 38 % of that observed without blockade, indicating that G‐induced cardioaccelera‐tion is predominantly due to sympathetic stimulation. G‐induced decline of cardiac output was more marked after propranolol, this effect being entirely due to the reduced response of the heart rate. In spite of the cardioinhibitory effects of propranolol, subjective G tolerance was well preserved; the response of the arterial mean pressure to increased G was unaffected due to a 65 % rise in systemic vascular resistance as against 43 % before propranolol. Hence, sympathetic chronotropic stimulation of the heart is not essential for the circulatory defense against increased gravitational stress. Transition from rest to exercise at 3 G produced a larger increase in stroke volume than in heart rate; after beta‐adrenergic blockade the dominance of the stroke xolume increase was exaggerated.
Hemodynamic Effects of Chloralose and Propranolol in Dogs
Authors: Halkola Lauri , Koivikko Antti , Länsimies Esko 
Published: December 2008

AbstractHeart rate, mean arterial pressure, cardiac output, and stroke volume (dye‐dilution method) were determined in 10 awake dogs. Then the animals were given propranolol and a‐chloralose. 5 dogs were β‐blocked before α‐chloralose and 5 dogs received the drugs in reverse order. The initial responses to the administration of the drugs were insignificant. The final cardiac output of dogs receiving Acta physiol. scand. 197.4 90. ‐chloralose first was lower than that of dogs receiving the same drugs in reverse order. The difference was due to (central or peripheral) α‐chloralose effect which weakende the cardiovascular ability to compensate a decrease of cardiac output. It was also observed that β‐blocking prevented and abolished the convulsions and tachnypnea caused by α‐chloralose.
5‐HT Storage in Rat and Rabbit Blood Platelets: The Separation of ATP‐Containing and Sulphomucopolysaccharide‐Containing Granules
Authors: Anderson Per , Slorach Stuart A. , Uvnäs Börje 
Published: December 2008

AbstractSonicated rabbit and rat platelets were subjected to differential centrifugation and the mixed organelle fraction so obtained then separated by ultracentrifugation on a discontinuous sucrose gradient. The distribution curves for 5‐hydroxytryptamine (5‐HT), histamine (studied in rabbit only) and adenosine‐5′‐triphosphate (ATP) were similar. Electron microscopy of the amine‐containing fractions revealed the presence of very dense granules. These fractions contained little or no hexosamine or35S, two indicators of the presence of sulphomucopoly‐saccharides (SMPS). A second type of granule, a‐granules, was found in fractions corresponding to peaks on the hexosamine and35S distribution curves. The observation that in rabbit 5‐HT, histamine and ATP are localized to the same subcellular fractions as the very dense granules agrees with the results of earlier workers. An analogous situation appears to exist in rat platelets. The biogenic function of the SMPS‐containing a‐granules remains uncertain. It might be suggested that they, like the mast cell granules, utilize their SMPS‐protein complex for the storage of electrically charged substances.
Efferent Chorda Tympani Activity and Salivary Secretion in the Rat
Authors: Hellekant Göran , Hagstrom Earl C. 
Published: December 2008

AbstractIt is known that nerve impulses to the mandibular salivary gland must be carried in the chorda tympani proper nerve, although they have never been recorded. This study presents recordings of efferent impulses in this nerve and simultaneous observations of secretion from this gland in rats under neuroleptic analgesia, during electrical stimulation of he salivary nuclei in the brainstem. Stimulation was found to increase the impulse activity in the nerve and to lead to secretion of saliva. The secretion ceased when the nerve was blocked. The relationship was best described by a straight line plot of the logarithm of the increased nerve activity against secretion, the correlation coefficient being 0.84. Barbiturate abolished the effect of brain stimulation. This indicates that nuclear structures, and not chorda tympani fibres, were being stimulated.
Activities of Rat Muscle Enzymes after Acute Exercise
Authors: Boström S. , Fahlén M. , Hjalmarson Å. , Johansson R. 
Published: December 2008

AbstractThe enzyme activities of rat gastrocnemius and cardiac muscle were measured immediately and at varying intervals up to 5 days after exhaustive swimming to study the onset and duration of enzyme changes. Immediately after exercise a decrease in the activities of hexokinase and phosphofructokinase was found in gastrocnemius muscle. The activities of various glycolytic, hexose monophosphate shunt and oxidative enzymes were increased in both muscles 1 and 3 days and were returned to control levels after 5 days. A decrease in RNA content was obtained in cardiac muscle immediately after exercise and an increase in RNA was seen in both muscles the day after exercise. In gastrocnemius muscle glycogen overshoot was found. Glucose tolerance was increased 1 day after the exhaustive swimming. It is concluded that the intensity of exercise and the interval between exercise and enzyme analysis have to be considered when studying adaptive responses in muscle enzyme activities
Motility of the Urinary Bladder in Cats during Filling at Physiological Rates: I. Intravesical Pressure Patterns Studied by a New Methods of Cystometry
Authors: Klevmark Bjørn 
Published: December 2008

AbstractNatural filling of the bladder has been studied by a new cystometric method termed “Controlled Slow Cystometry” (CSC). A suprapubic double‐catheter was used for filling from a constant‐volume infusion pump and for continuous intravesical pressure recording. A rate‐unit and 5 rate‐models were proposed for the filling procedure. The rate‐unit was defined as the normal hour‐diuresis (HD) using 26 ml/kg per day as a normal value. The rate‐models were considered as physiological and relevant to illustrate the normal variations in excretion of urine. Maximal physiological increase in urinary excretion was measured to be 15 times the normal. Intravesical pressure recording was performed during filling from the pump according to the rate‐models as well as during normal and increased urinary excretion (5 % glucose i.v.). A differentiated pressure reaction related to the rate of filling was found. Below the rate of 2.4 HD the pressure curve was flat. Pressure increase started at individual rates between 2.4–7 HD. When the rate fell below this value the pressure stabilized at a higher level (pressure accumulation phenomenon). Accordingly, micturition was elicited in the same animal at clearly separated pressure levels depending on the foregoing rates of filling. The pressure patterns demonstrated are considered as basic motility reactions present during natural filling.
A Microspectrophotometric Technique for Determination of Respiration in Comparison to the Cartesian Diver Method. —Respiratory Activity of Rat Corpus Luteum Cells with Reference to Substrate
Authors: Herlitz H. , Hultborn R. 
Published: December 2008

AbstractA comparative study of two microrespirometric methods, the classical standard‐diver technique and a newly introduced spectrophotometric procedure, using hemoglobin as indicator of oxygen tension as well as donor of oxygen, has been performed on small samples of well‐defined rat corpus luteum tissue. Oxygen consumption of this tissue was determined in absence of substrate as well as in the presence of oxalacetate and succinate, respectively. The accuracy of the two methods was equal though small differences in absolute values were found. Rapidity and simplicity of performance is considerably increased with the spectrophotometric procedure. Endogenous respiration was found to be approximately 1 μl O2/mg dry weight × h, and in the presence of oxalacetate oxygen consumption was increased by 50 per cent. In the presence of succinate respiration was increased to about 10 μ O2/mg dry weight × h.
Differentiation of the Contractile Effects of Prostaglandin E2and the C‐Terminal Octapeptide of Cholecystokinin in Isolated Guinea‐pig Gallbladder
Authors: Andersson Karl‐Erik , Hedner Pavo , A Persson Carl G. 
Published: December 2008

AbstractIn the isolated guinea‐pig gallbladder, contractions were induced by acetylcholine (ACh), the C‐terminal octapeptide of cholecystokinin (C8‐CCK), prostaglandin E2(PGE2), and the prostaglandin precursor arachidonic acid (ARA). The effects on these contractions induced by the inhibitor of the prostaglandin synthesis indomethacin, and of the prostaglandin antagonists polyphloretin phosphate (PPP), and SC 19220 were investigated. In a concentration of 0.5 μg/ml indomethacin inhibited the response to ARA but did not appreciably affect the contractions produced by ACh, C8‐CCK and PGE2. Indomethacin, 10 μg/ml, reduced the responses to all the agonists probably due to a non‐specific depressive effect. PPP, 1–10 μg/ml, had no effects on the contractions elicited by ACh, C8‐CCK and PGE2. In concentrations of 100–400 μg/ml, PPP caused a transient contraction in the gallbladder strips and reduced the responses to the agonists used. SC 19220, 2 and 8 μg/ml, selectively inhibited the responses to ARA and PGE2, leaving the contractions of ACh and C8‐CCK virtually unaffected. The inhibition of the response to PGE2was surmountable by increasing the bath concentration of the prostaglandin 5–100 times.—It is concluded that local synthesis and release of prostaglandins play no essential role for the mediation of the contractile effect of C8‐CCK in guinea‐pig gallbladder.
The Effects of Physical Exercise on Fat Cell Metabolism in the Rat
Authors: Kral J. G. , Jacobsson B. , Smith U. , Björntorp P. 
Published: December 2008

AbstractRats trained by repeated swimming bouts were compared with rats swimming once and with sedentary controls. Training caused a decrease in body weight, body triglyceride and fat cell size. Fasting plasma insulin was also decreased. However, plasma free fatty acids and glycerol were not changed. Incorporation of labelled glucose into fat cell triglycerides was decreased by physical training, which also caused a disappearance in the fat cell size dependence of adipose tissue glucose metabolism. The response to insulin of this pathway in enlarged fat cells was increased by physical training. After a single exhaustive swim the cell size dependence of triglyceride labelling of adipose tissue apparently also disappeared. It was suggested that physical training leads to an adaptation of adipose tissue metabolism with an increased insulin sensitivity. This effect as well as the disappearance of the cell size dependence of adipose tissue metabolism might hypothetically be due to a diminished glucose flow to adipose tissue caused by exercise.
A Pharmacological Study of Intestinal Vasodilator Mechanisms in the Cat
Authors: Biber Björn , Fara John , Lundgren Ove 
Published: December 2008

AbstractThe intestinal vasodilator responses evoked by close i.a. administration of cholecystokinin (CCK) and secretin, mechanical stimulation of the mucosa and transmural electrical field stimulation were abolished by the 5‐hydroxytryptamine (5‐HT) antagonist dihydroergotamine, given in doses sufficient to block the vascular effects of i.a. injected 5‐HT. Corresponding results were obtained by making the cat small intestine tachyphylactic to 5‐HT. Nervous blockade (tetrodotoxin), inhibiting the intestinal blood flow increase after mechanical mucosal or electrical field stimulation, left the vascular responses to exogenous CCK and secretin unaffected. An increased 5‐HT content in venous blood from the intestine was demonstrated during vasodilatations caused by electrical field stimulation. A participation of intestinal 5‐HT, possibly as a transmitter substance, in the vasodilator mechanism evoked by mechanical mucosal stimulation or electrical transmural field stimulation is suggested.
Cardiovascular Responses to Acute Mental ‘Stress' in Spontaneously Hypertensive Rats
Authors: Hallbäck Margareta , Folkow Björn 
Published: December 2008

AbstractSpontaneously hypertensive rats (SHR), aged 7 months (‘manifest’ hypertension) or 10–11 weeks (‘prehypertensive’), and renal hypertensive rats (RHR; ‘nonhereditary’ hypertension were compared with normotensive rats (NCR) concerning cardiovascular responses to mental ‘stress’. Blood pressure and heart rate were followed in pairs of awake SHR—NCR and RHR—NCR, while defence reactions were provoked by alerting stimuli (light, noise, vibrations). The tachycardia, here involving both accentuated sympathetic and centrally suppressed vagal discharge, reflected the intensity of neural activation and the pressuie rise the imposed load on heart and vessels. In both respects the SHR groups responded decidedly stronger than NCR and RHR, also after either adrenergic or vagal cardiac blockade. Since SHR and NCR hearts responded equally to graded vagal stimulations or to isoprenaline, the enhanced tachycardia responses reflected a truly intensified defence reaction in SHR. Further, SHR responded more often to mild stimuli than NCR, suggesting a lower ‘threshold’ for defence reactions, and more frequently with clearcut defence reactions than NCR which exhibited vagal bradycardia responses in 30 %, versus 5 % in SHR. This hyperreactivity and apparent prevalence concerning ‘sympathotonic’ patterns in SHR during alertness, in turn tending to trigger structural vascular adaptation and manifest hypertension, is evidently genetically linked and not secondary to hypertension, being observed particularly in ‘prehypertensive’ SHR but not in RHR.
The Influence of Temperature on the Force‐Velocity Relationship in Rabbit Papillary Muscle
Authors: Edman K. A. P. , Mattiazzil Alicia , Nilsson E. 
Published: December 2008

AbstractThe force‐velocity relationship was determined at the moment of isometric peak twitch force in rabbit papillary muscles using the damped‐release technique described previously. The analysis was carried out in each muscle at two or three temperatures within the range 22–338deg; C. The experimental data were fitted with Hill's equation by means of a computer program using the least squares method. Lowering of the temperature caused an increase of the isometric peak twitch force (Po) and also, generaliy, an increase of the extrapolated value of Vmax (the shortening velocity at zero load). The temperature‐induced changes of the force‐velocity curve were interpreted as being the net result of two opposing effects: I. an altered degree of activation of the contractile system caused by a change in the amount of activator‐calcium bound to the contractile proteins (‘inotropic temperature effect’), and 2. a change in the rate of interaction between the A and I filaments independent of the degree of activation (‘specific temperature effect’). The analysis indicated a Q10 of 1.9 for the specific temperature effect. This value accords with the temperature dependence of Vmax that has been observed during tetanic contraction of skeletal muscle.
Insulin Sensitivity in Rats with Ventromedial Hypothalamic Lesions
Authors: Hongslo C. Fahle , Hustvedt B. E. , Løvø A. 
Published: December 2008

AbstractThe insulin sensitivity of the diaphragm and parametrial adipose tissue in animals with ventromedial hypothalamic (VMH) lesions and controls were assayed in vivo by studying the intra‐peritoneal action of exogenous insulin. Lipogenesis and glycogen synthesis were stimulated to the same extent in lesioned and control animals. This implies that the co‐existence of hyper‐insulinemia and normoglycemia previously demonstrated in lesioned animals cannot be attributed to decreased insulin sensitivity. Increased gluconeogenesis in the lesioned animals is indicated by elevated levels of plasma urea. This may contribute to the maintainance of normoglycemia in the presence of hyperinsulinemia and normal insulin sensitivity. It is suggested that the profound metabolic effects of VMH destruction is caused by a disturbance in the nervous control of gastro‐intestinal functions. This may lead to alterations in the endocrine pancreatic secretion, and possibly also in liver metabolism.
Distribution of Carbonic Anhydrase in the Frog Nephron
Authors: Lonnerholm Udmar , Ridderstrale Yvonne 
Published: December 2008

AbstractThe distribution of carbonic anhydrase in the kidney of the frog (Rana temporaria) was studied by the histochemical method of Hansson, using light and electron microscope. In all cells showing enzyme activity, the staining deposits seemed to be diffusely distributed without any consistent local accumulation. The proximal tubule contained no or little enzyme. Some part of the distal tubule showed high enzyme activity, whereas the remainder was inactive. In the initial collecting tubule a mosaic pattern of stained and unstained cells was found, the stained cells being identical with the so called canaliculi cells. The collecting duct contained some stained cells, too. The renal corpuscle, the neck and the intermediate segment were inactive. Apparently the enzyme is less widely distributed along the kidney tubules of the frog compared to the tubules of man and rat, where enzyme activity is found in the convoluted part of the proximal tubule, the whole distal tubule and in many cells in the collecting duct. These differences in enzyme distribution as well as certain physiological data might indicate differences in the localization of the urinary acidification between the frog and these mammals.
The Effect of Barbiturate on Retinal Functions. I. Effects on the Conventional Electroretinogram of the Sheep Eye
Authors: Kna've Bengt , Persson Hans E. 
Published: December 2008

AbstractThe present work is the first in a series of investigations on the effect of barbiturate on retinal functions. The changes in the conventional ERG of the dark‐adapted, intact sheep eye were studied after i.v, administration of an ultra‐short acting barbiturate, thiopental. After injection of small and moderate doses (< 20 mg/kg), the a‐ and b‐wave amplitudes were found to increase. Larger doses resulted in a further enhancement of the a‐wave amplitude, whereas that of the 6‐wave diminished. Transient falls in the arterial blood pressure were also recorded after barbiturate administration. Since effects on mammalian ERG of alterations in retinal blood circulation have been the subject for discussion, the ERG was studied after lowering the blood pressure by electrical stimulation of the free‐dissected left vagal nerve. The reduction in blood pressure obtained in this way was recorded without concomitant changes in the ERG. For this reason we exclude the possibility of a barbiturate mediated reduction in blood pressure as the mechanism behind the changes in retinal function of the intact sheep eye after administration of, at least, small doses of barbiturate.
Utilization of Energy Reserves by Cells Isolated from Newborn Rat Brain
Authors: Hemminki Kari , Härkönen Matti 
Published: December 2008

AbstractCells were isolated from newborn rat brain cortex as previously described (Hemminki 1972 a). The viability of the isolated cells was evaluated by determining the concentrations of the major energy metabolites during incubation in various conditions. In isolated cells the initial concentrations of glycogen, ATP and phosphocreatine were 2.8, 7.1 and 7.8 mmol/kg protein, respectively. These concentrations were lower than in newborn rat brain cortex in situ, while the concentrations of ADP, AMP, pyruvate and lactate were higher in the isolated cells. When the isolated cells were incubated in air without glucose the levels of ATP, phosphocreatine and glycogen decreased slowly. In a N2‐saturated incubation medium the decrease was more rapid. When exogenous glucose was added and the incubations carried out in air the levels of ATP and phosphocreatine increased to 130 and 170 % of the starting concentrations, respectively. These experiments indicate that the cells are metabolically active.
Rate and Extent of Adaptive Cardiovascular Changes in Rats during Experimental Renal Hypertension
Authors: Lundgren Yen , Hallback Margareta , Weiss Lilian , Folkow Bjorn 
Published: December 2008

AbstractTo study the extent and exact time course of cardiovascular structural adaptation to increases in pressure load, renal hypertension was induced in normotensive male Wistar rats by renal artery constriction. At different intervals after operation the hemodynamic characteristics of the hypertensive rats and normotensive control rats were explored in paired hindquarter perfusions, from maximal dilatation up to maximal constriction (cf, Folkow et al, 1970 b). At the same time intervals the extent of left ventricular hypertrophy and of water content of the aortic wall were examined. The results reveal the presence of left ventricular hypertrophy in the hypertensive rats already after one week, soon followed by adaptive structural changes of the resistance vessels, in the form mainly of media hypertrophy, these processes being largely completed 2–3 weeks after operation. In these animals, lacking genetic predisposition for hypertension, the extent of the structural vascular changes seems large enough to explain a considerable part, but not all, of the pressure rise. An increased water content of the hypertensive aortic wall is found first 4.5 months after operation, indicating that some water logging of arterial and maybe also arteriolar walls might occur in late phases of chronic renal hypertension.
The Effect of Extracellular Calcium on Thermal Excitability of the Sensory Units in the Tooth of the Cat
Authors: Olgart Leif , Haegerstam Glenn , Edwall Lennart 
Published: December 2008

AbstractIntradental sensory nerve impulse activity was measured from dentinal cavities in canine teeth of anesthetized cats. No spontaneous activity was usually recorded in cavities filled with isotonic saline. Heat stimulation of 15–20oC failed to give any impulse activity, while other stimuli, such as air blasts produced bursts of impulses. Lowering extracellular calcium ion concentration. by local application of sodium citrate, sodium oxalate or EDTA, induced impulse activity. Under these conditions, heat produced a rapid increase in discharge activity. which lasted as long as the stimulus was applied. Increased extracellular calcium concentration abolished this response to heat. The present findings show that a change in the extracellular calcium ion concentration modulates the excitability of intradental sensory units, and may thus also modulate the resulting experience of pain.