bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Changes in Plasma Na+ and Ca++ Ion Concentration on Body Temperature during Exercise
Authors: Nielsen Bodil 
Published: December 2008

AbstractPlasma osmolarity and plasma Na+ and Ca++ ion concentrations were changed in human subjects by having them drink hypertonic solutions of NaCl or CaCl2. Plateau values of body temperature during work were raised by increase in [Na+] and lowered by increase in [Ca++] compared to values in normal conditions. The effect on body temperature could be ascribed to a faster onset of sweating in the Ca++ experiments and a slower onset in the Na+ experiments. The effect on body temperature of increased osmotic concentrations in plasma was due to action of the specific ions rather than a general effect of change in osmolarity. It was not possible to show whether the effects of Na+ and Ca++ were due to action on the central nervous system and thermoregulatory centers, or to peripheral interference with the function of the sweat glands.
Quantitative Measurement of Blood Flow and Oxygen Consumption in the Rat Brain
Authors: Norberg K. , Siesjö B. K. 
Published: December 2008

AbstractThe cerebral blood flow (CBF) and oxygen consumption (CMRO2) were determined in rats under superficial (N2O) anesthesia. The CBF was measured with a Xenon133modification of the Kety and Schmidt principle, using arteriovenous sampling during the desaturation of the tissue following a 20 min saturation period. The CMRO2 was calculated from the CBF and from the arteriovenous difference in total oxygen content. Since venous blood was sampled from the superior sagittal sinus the values for CBF and CMRO2 are probably representative of cortical tissue. Control experiments with measurement of Xenon133activities in arterial blood and in tissue, as well as in blood from different cranial veins, showed that the tissue under study contained no slowly perfused masses, and that significant contamination of superior sagittal sinus blood with blood from extracerebral sources did not occur. The results demonstrate that the blood flow of the rat cerebral cortex is 2–3 times higher, and the oxygen consumption 3–4 times higher, than the corresponding values for the human brain. These differences partly reflect a difference between cortical tissue and whole brain but an inverse relationship between body size and cerebral metabolic rate also seems involved.
High Energy Phosphate Compounds in Adipose Tissue: The Effect of Hemorrhage
Authors: Fredholm B. B. , Fronek A. 
Published: December 2008

AbstractThe levels of ATP and CP in gastrocnemius muscle and inguinal subcutaneous adipose tissue of cats were measured before and after withdrawal of 25–45 per cent of the calculated blood volume and after retransfusion of the shed blood. Resting values were in skeletal muscle: ATP‐6.77±0.49 μmol/g tissue, CP‐17.35 ±1.31 μmol/g tissue (mean ± S.E.), and in adipose tissue: ATP 86.7 ±18.1 and CP 132.8± 8.5 nmol/g. Within 10 min after withdrawal of blood, muscle high energy phosphate levels were unchanged whereas adipose tissue CP and ATP levels had dropped to 20 and 48 per cent of control, respectively. Later during the hypotensive period, skeletal muscle levels also fell. Following retransfusion of the shed blood, adipose tissue levels remained low, whereas skeletal muscle levels returned towards control. The results demonstrate that the high energy phosphate levels are more severely decreased in adipose tissue than in skeletal muscle following bleeding in cats, and that the fall is not reversible in adipose tissue in contrast to muscle. The results are compatible with the idea that adipose tissue is one of the organs in which irreversible changes following hemorrhage are manifested.
Effects of 3‘, 5’‐Cyclic Adenosine Monophosphate, 5‐Hydroxy‐tryptamine, Noradrenaline and Theophylline on the Simultaneous Release of Peroxidase and Amylase from the Guinea Pig Submanibular Gland
Authors: Carlsöö Bengt , Danielsson ÅKe , Marklund Stefan , Stigbrand Torgny 
Published: December 2008

AbstractNoradrenaline (NA), 5‐hydroxytryptamine (5‐HT) and N6,2‐0′‐dibutyryl cyclic adenosine monophosphate (DBcAMP) induced a parallel discharge of peroxidase and amylase from the guinea pig submandibular glandin vitro.Theophylline alone, at a concentration of 5 mM, had only little effect on enzyme secretion, but it markedly potentiated the effects of noradrenaline, 5‐HT and DBcAMP at submaximal concentrations. Adenosine‐3′‐monophosphoric acid (3′‐AMP) and adenosine‐5′‐monophosphoric acid (5′‐AMP) were without effect on enzyme secretion. Maximal effects of NA and DBcAMP on enzyme release were obtained at concentrations of 0.01 mM and 3 mM respectively. Dose‐response curves for the stimulation of peroxidase and amylase release by 5‐HT revealed that this amine was a potent secretagogue at the concentrations of 0.1 and 0.3 mM but was less effective at higher concentrations. It is concluded that peroxidase and amylase are simultaneously secreted from the guinea pig submandibular gland, and that the release of both enzymes is mediated via cyclic AMP.
Histochemical Studies on Adenosine Triphosphatase Activity in the Rat Cornea
Authors: Tervo Timo , Palkama Arto 
Published: December 2008

AbstractNaK‐ATPase activity in the rat cornea was studied histochemically. The enzyme activity was localized in all epithelial cell layers in their cell membranes, in the Schwann cells and nerve fibers, possibly in the stromal keratocytes and in the endothelial cell membranes. When sodium and potassium were omitted from the incubation solution, a similar localization of the histochemical reaction was obtained, but the intensity of the reaction became significantly weaker. When the corneas had been pre‐incubated in a buffer solution containing 3 times 10‐4M of ouabain, and subsequently incubated with or without 70 mM NaCl and KCl in the incubation solution, a clear inhibition of the enzyme reaction was noted. This was accepted as a proof for the specificity of the histochemical enzyme technique. The histochemical NaK‐ATPase reaction was also inhibited after intraocular ouabain injections. The histochemical method for NaK‐ATPase used in the present study is discussed as well as the significance of the localization of the enzyme in the different structures of the cornea.
Cardiorespiratory Responses to Graded Exercise at Increased Ambient Air Pressure
Authors: Fagraeus Lennart , Hesser Carl Magnus , Linnarsson Dag 
Published: December 2008

AbstractThe separate and combined effects of increased inspired oxygen and nitrogen pressures on cardiorespiratory and metabolic responses to graded exercise (50, 100, and 150 W) were assessed by comparing data from identical work experiments performed under three different ambient conditions, viz. with the subjects breathing (A) air at 1.0 ATA, (5) oxygen at 1.0 ATA, and (C) air at 4.5 ATA (same inspired Po3 as in B). In general, the physiological responses to the various work loads were qualitatively similar in the three conditions, but for a given load quantitative differences were observed. By comparing Condition C with A it was found that a rise in both the O2 and N2 pressures resulted in the following changes at the highest work load: significant increments in Vos, Vco2, end‐tidal and mixed expired Pco2, and oxygen pulse (Vo2 per heart beat), significant reductions in heart rate, VD, VD/VT, and ventilatory equivalents for oxygen (v̇I/v̇CO2) and carbon dioxide (v̇I/v̇CO2), and no consistent changes in Vi and respiratory exchange ratio. When related to v̇O2, i.e. to the metabolic rather than the ergometric load, Vi was lower in C than in A. By comparing Condition B with A, and C with B, evidence was obtained that the above changes in Vi, Pco2, ventilatory equivalents, oxygen pulse, and heart rate were caused in part by the rise in O2 pressure, and in part by factors related to the rise in N2 pressure, whereas the changes in VD and VD/VT were due mainly to the raised O2 pressure, and the changes in Vo2 and Vco2 to the raised Ns pressvire.
Regression of Structural Cardiovascular Changes after Reversal of Experimental Renal Hypertension in Rats
Authors: Lundgren Yen 
Published: December 2008

AbstractRenal hypertension was induced in young normotensive male Wistar rats by constriction of one renal artery. This constriction was released 3–4 weeks later when pressure had stabilized around 180 mm Hg and when the structural cardiovascular adaptation to this hypertensive level was largely completed (Folkow et al. 1973, Lundgren et al. 1974). 1, 3, 7, 14 and 25 days later paired hindquarter perfusions were performed on one declipped renal hypertensive rat (D‐RHR) and one normotensive control rat (NCR), exploring the design of the resistance vessels as expressed by the resistance at maximal vasodilatation, the maximal slope of the dose‐response curve to noradrenaline and the maximal pressor response (cf. Folkow et al. 1970 b). At the same time intervals the left heart ventricles of all animals were weighed. Already one day after declipping, arterial pressure was normalized while the hemodynamic analysis indicated that the D‐RHR resistance vessels, like the left ventricle, still showed largely unchanged hypertrophic changes characterizing hypertension. Then, however, a rapid regression of these changes occurred, being considerable already after 7–14 days, and after about 3 weeks the design of both heart and resistance vessels had become fully readapted to normotensive levels.
Electrophysiological Investigation of the Projection of Secondary Muscle Spindle Afferents in the Cat Spinal Cord
Authors: Fu T. C. , Schomburg E. D. 
Published: December 2008

AbstractThe intraspinal projection of functionally identified secondary muscle spindle afferents from tenuissimus and medial gastrocnemius was investigated in anesthetized cats. Centrally and peripherally intact single fibres were recorded in the L7 dorsal root. The spinal projection of their axonal branches was traced out by antidromic intraspinal microstimulation (lowest threshold 1.6‐6.0 μA). Collaterals of the investigated fibres were found not only in the dorsal funiculus, the dorsal horn and the intermediate region, but also in the ventral horn close to the motor nucleus or even reaching into it. These findings in conjunction with the results regarding group II focal synaptic potentials (Fu et al. 1974) suggest the existence of two main populations of first order interneurones activated from secondary spindle afferents located in the dorsal and ventral horn, respectively. The central delay of the antidromically conducted group II impulses indicated a substantial reduction of their effective conduction velocity within the spinal cord.
Uptake of Iodinated Oxytocin by Some Tissues and Organs in the Male Rat
Authors: Agmo Anders 
Published: December 2008

AbstractThe tissue distribution of 125,I‐oxytocin was studied shortly after injection of 40 mU into male rats. There appeared to be a gradual accumulation of radioactivity in the neurohypophysis, and a specific uptake was observed in the vas deferens. The radioactivity content was also studied in extracts prepared from the hypophysis in animals killed 30 or 240 s after injection. There appears to be a very rapid catabolism both in the neuro‐ and adenohypophysis, since radioactivity was found in several substances already 30 s after injection of intact hormone. The uptake pattern in the various tissues is discussed in relation to known or suggested functions of oxytocin in the male.
Stimulation of Glucose Metabolism in Rat Mast Cells by Antigen, Dextran and Compound 48/80, Used as Histamine Releasing Agents
Authors: Chakravarty Nirmal , Sørensen Hans Jorgen 
Published: December 2008

AbstractHistamine release in aerobic medium from rat peritoneal mast cells by anaphylactic reaction, dextran and compound 48/80 was associated with a stimulation of exogenous glucose metabolism as determined by carbon dioxide and lactate production. There was generally a correlation between the amount of histamine released and the degree of metabolic stimulation. In anaerobic medium a stimulation of lactate production was observed in most of the experiments when histamine was released by anaphylactic reaction and dextran. Compound 48/80‐induced histamine release in presence of oligomycin was not, however, associated with any appreciable change in lactate production. Galactose and fructose were metabolized by rat mast cells to CO2 and lactate, but the rate of CO2 production was only 18 % and 29%,respectively, and that of lactate production (aerobic) 5 % and 3.6 %, respectively, as compared to the metabolism of glucose to these products under the same conditions. 80 mM galactose could partially reverse the cyanide inhibition of histamine release while the same concentration of fructose was ineffective.
Time Course and Extent of Structural Vascular Adaptation to Regional Hypotension in Adult Spontaneously Hypertensive Rats (SHR)
Authors: Weiss Lilian , Hallbäck Margareta 
Published: December 2008

AbstractIn female spontaneously hypertensive rats, 8–12 months old and consequently with considerable structural changes in their resistance vessels, the aorta was ligated below the renal arteries, markedly lowering the hindquarter blood pressure. 3, 7, 14, 21 and 135 days later the hindquarters of these rats and of control rats were subject to paired perfusions, from maximal dilatation up to maximal pressor responses, thus exploring hemodynamically the rate and extent of regressive changes in vascular design. ‐ Already after 3 days clear signs of regression of the hypertensive vascular changes were found and in about 3 weeks the resistance vessels had almost completed their considerable adjustment to the low pressure situation, with widened lumina and a reduced bulk of contractile media. However, still after another 17 weeks they displayed signs of a wall /lumen ratio elevation compared with the situation in similarly treated young SHR (Folkow et al. 1971 a). ‐ It is concluded that even though a considerable hypotensive readjustment of vascular design takes place also in adult SHR with established hypertension, it is generally more difficult to induce full regression the higher the age and the longer the duration of the disease, presumably due to the gradual addition of less reversible vascular changes such as collagen invasion of the media.
Discharge Properties of Motor Units in Relation to Recruitment Order in Voluntary Contraction
Authors: Hannerz Jan 
Published: December 2008

AbstractThe discharge pattern and recruitment order of single motor units in voluntary contraction of the normal human anterior tibial muscle was studied with an electrode having a high selectivity and a high positional stability in the muscle. In sustained contractions each motor unit was activated at a characteristic level of tension. The higher the threshold of the motor unit in sustained contraction, the higher was the frequency when the unit attained a discharge at regular intervals and the higher tended the “maximum frequency‘‐of the unit to be. Motor units with low thresholds in sustained contractions exhibited a continuous or tonic discharge in strong sustained contractions, whereas units with high thresholds tended to exhibit a discontinuous or phasic discharge. For some units the threshold of activation remained stable, for others it increased during activity. In twitch contractions the recruitment order of motor units differed considerably from that in sustained contractions.
Blood Pressure and Vascular Design in Renal Hypertension in Rats after Prolonged Propranolol Treatment
Authors: Lundgren Yen 
Published: December 2008

AbstractTo study the effect of β‐adrenergic blockade on the development of renal hypertension, propranolol was given by administration in the drinking water to 4 week old normotensive male Wistar rats. After 3 weeks of treatment the left renal artery was constricted by a silver clip in order to induce renal hypertension, the same procedure being performed in a group of matched untreated controls. ‐ The incidence and degree of hypertension 4 weeks after renal artery constriction was about the same in both groups, but heart rate was considerably‐lower in the propranolol‐treated animals, and heart rate responses to isoprenaline were diminished. Treatment was continued until 4 weeks after constriction, when quantitative hemodynamic analysis of the hindquarter vascular beds revealed the same degree of structural vascular changes in both treated and untreated renal hypertensive rats. ‐ Another group of rats, in which renal hypertension and hypertensive cardiovascular changes were already established, was treated with propranolol for 3 months. No effect on arterial pressure was noticed, but heart rate was considerably reduced. Thus, renal hypertension appears to be unaffected by adrenergic β‐receptor blockade, in contrast to the situation in early phases of hypertension in spontaneously hypertensive rats (Folkow, Lundgren and Weiss 1972).
Sympathetic Skin Nerve Activity and Skin Temperature Changes in Man
Authors: Normell Lars A. , Wallin B. Gunnar 
Published: December 2008

AbstractSimultaneous recordings of skin temperature and efferent sympathetic impulse activity in cutaneous nerve fascicles were made in two healthy subjects and in one patient with paraplegia due to a transverse lesion of the spinal cord at the level of the first lumbar segment. In the patient the recordings were made below the level of the lesion in a skin area deprived of sensibility but with preserved temperature responses to indirect heating and cooling. The sympathetic nerve activity showed the same characteristics both in the paraplegic patient and in the healthy subjects. Evoked changes in sympathetic nerve activity were followed by changes in skin temperature of the same type in all three subjects. The demonstration of concomitant changes in evoked sympathetic nerve activity in a peripheral nerve and in skin temperature in the corresponding skin area strongly supports the concept that the cutaneous thermoregulatory vasomotor response (CTVR), is a consequence of changes in efferent sympathetic nerve activity. The results demonstrate that loss of somatic sensation and voluntary motor function can be combined with a functionally intact efferent sympathetic pathway below the level of a “complete” lesion of the spinal cord.
The Immediate Effects of Ligation of the Hepatic Artery on Liver Hemodynamics and Liver Function in the Cat
Authors: Krarup Niels , Larsen Jens Anker 
Published: December 2008

AbstractCats in thet postabsorptive state and anesthetized with chloralose where used for the experiments. In 7 out of 8 expts. ligation of the hepatic artery caused no change in the hepatic elimination rate of ethanol, the secretion rate of bile and Indocyanine Green (IGC), the hepatic oxygen consumption or the output of glucose and lactate, whereas a small decrease in hepatic ketone production was noticed. Ligation caused a 16 per cent decrease in ICG‐clearance and a 60 per cent increase in the extraction ratio of ICG, which can be explained by the reduction in total liver blood flow. In one experiment in which the initial hepatic oxygen consumption was relatively high ligation caused a fall in hepatic oxygen consumption with marked changes in liver function as a consequence. It is concluded that the main function of the hepatic artery is to supply the liver as a whole with oxygen whereas no specific functions of the artery were demonstrable.
Effects of Prolonged Treatment with Adrenergic β‐receptor Antagonists on Blood Pressure, Cardiovascular Design and Reactivity in Spontaneously Hypertensive Rats (SHR)
Authors: Weiss Lilian , Lundgren Yen , Folkow Björn 
Published: December 2008

AbstractYoung “prehypertensive” SHR were treated with two kinds of β‐adrenergic receptor antagonists from 2 1 / 2 up to 8 months of age. Arterial pressure largely remained at prehypertensive levels and acute cardiovascular responses to “stress” were considerably modified compared to untreated SHR. Quantitative hemodynamic analyses revealed that resistance vessel design exhibited only slight hypertensive changes when related to untreated controls, while the development of left ventricular hypertrophy was far less influenced by the treatment. In part of the group, pressure was followed for another 6 months after treatment, showing only a delayed and modest pressure rise compared with untreated, matched SHR. When instead adult SHR, with “established” hypertension, were similarly treated from 8 up to 10 months of age, resting arterial pressure remained unaffected and the resistance vessels exhibited only modest regression of the hypertensive changes, with signs of a largely preserved increase of vascular wall/lumen ratio, and with negligible regression of cardiac hypertrophy. The results indicate that early, “preventive” treatment of SHR with β‐receptor blockers is of considerable value whichever their exact modes of action, though some regression of vascular changes can be achieved also in established hypertension, particularly in females (Weiss 1974).
Afterhyperpolarization Conductance Time Course in Lumbar Motoneurones of the Cat
Authors: Baldissera By F. , Glstafsson B. 
Published: December 2008

AbstractThe time and potential dependence of the conductance process (es) underlying the longlasting afterhyperpolarization (AHP) in the cat's a‐motoneurones were studied. The conductance changes were determined by injection of short current pulses. The conductance time course was characterized by a longlasting exponential decay interrupted by a plateau corresponding to the slower hypcrpolarizing phase of the AHP. By displacing the membrane potential in the subthreshold region with the injection of longlasting current pulses it was found that the conductance was largely unaffected by membrane potential displacements. Similar characteristics were found when calculating the AHP conductance time course from the AHP voltage. It was concluded that the AHP in motoneurones is given by a potassium conductance process with this complex S‐shaped time course. A mathematical expression describing this time course is given.
Firing Behaviour of a Neurone Model Based on the Afterhyperpolarization Conductance Time Course. First Interval Firing
Authors: Baldissera By F. , Gustafsson B. 
Published: December 2008

AbstractThe firing behaviour of a neurone model, in which the refractoriness is solely governed by a longlasting potassium conductance process with a time course similar to that underlying the afterhyperpolarization in a‐motoneurones (Baldissera and Gustafsson 1974 a) is described. The frequency‐current relation in the model is shown to display the 3 firing ranges found in real motoneurones (Kernell 1965 b, Schwindt 1973). With increasing current injection the inter‐spike voltage traJectories in the model are also undergoing the same peculiar modifications as described for real motoneurones (Schwindt and Calvin 1972, Schwindt 1973). A re‐examination of the first interspike interval in real motoneurones revealed earlier not recognized firing behaviour predicted by the mode]. It is concluded that the model is well simulating the firing behaviour of the first interspike interval in a‐motoneurones.