bluuebunny/crossref_metadata_2025 huggingface dataset:
Activities of Rat Muscle Enzymes after Acute Exercise
Authors: Boström S. , Fahlén M. , Hjalmarson Å. , Johansson R.
Published: December 2008

The 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

Natural 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

A 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

In 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

Rats 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

The 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

Spontaneously 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

The 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

The 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

The 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

The 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

Cells 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

To 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

Intradental 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.
Effect of Changes in Plasma Na+ and Ca++ Ion Concentration on Body Temperature during Exercise
Authors: Nielsen Bodil
Published: December 2008

Plasma 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

The 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

The 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

Noradrenaline (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

NaK‐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

The 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

Renal 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

The 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

The 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

Histamine 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

In 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

The 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

To 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

Simultaneous 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

Cats 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

Young “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

The 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

The 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.
Transport and Oxidation of Amino Acids and Glucose in the Isolated Exocrine Mouse Pancreas: Effects of Insulin and Pancreozymin
Authors: Danielsson Ake , Sehlin Janove
Published: December 2008

The uptake and oxidation of L‐alanine and L‐leucine as well as the oxidation of D‐glucose were studied in pieces of microdissected exocrine mouse pancreas. The main observations and conclusions were as follows. The rate of oxidation of D‐glucose was low and was only slightly enhanced by increasing its concentration in the medium from 3 to 20 mM. Even at a concentration as low as 0.1 mM, both amino acids were oxidized at a higher rate than D‐glucose. Thus, mouse exocrine pancreas seems to prefer amino acids to D‐glucose as substrate for its energy metabolism. The uptake of L‐alanine and L‐leucine in the exocrine cells was studied with a double‐label technique using 14C‐L‐glucose as an extracellular marker. Both amino acids were rapidly taken up and accumulated in the exocrine cells. D‐glucose inhibited both the uptake and oxidation of L‐alanine. The decreased rate of oxidation of this amino acid might have been due to the reduction in uptake. Stimulation of secretion by cholecystokinin‐pancreozymin increased the oxidation of D‐glucose, L‐alanine and L‐leucine. However, no effect on the transport of the amino acids into the exocrine cells was observed. Therefore the effect of CCK‐PZ on oxidation seems not to depend on an increased uptake of the amino acids. The presence of insulin (100 /<g/ml) stimulated the oxidation of D‐glucose, but not that of the amino acids. Insulin had no effect on the transport of the amino acids into the exocrine cells.
Comparison of the Lipolytic Activity of Circulating and Locally Released Noradrenaline during Acidosis
Authors: PaulHjemdahl  , Fredholm BertilB.
Published: December 2008

The influence of hypercapnic acidosis on the effects of i.v. noradrenaline (NA) infusions and of sympathetic nervous stimulation were studied in the isolated autoperfused subcutaneous adipose tissue of the dog. Acidosis increased resting vascular resistance in the adipose tissue. Infusion of NA (0.35‐0.69, μg/kg/min for 30 min) increased adipose tissue blood flow at both pH 7.4 and 7.0. Arterial increases in glycerol and FFA due to NA infusions were inhibited by 60–70 % during acidosis. Mobilization of these lipolytic products from the adipose tissue was impaired to the same degree. Sympathetic nervous stimulation (4 Hz for 5 min) lead to the same increase in vascular resistance at normal and acid pH. The lipolytic response,i.e.glycerol release, to nerve stimulation was unaffected by acidosis. FFA release was, however, reduced by about 40%.Release of3H‐NA by nerve stimulation from previously labelled adipose tissue was not significantly increased during acidosis. We conclude that inhibition of NA induced increases in arterial glycerol and FFA concentrations by acidosis can be explained by impaired mobilization from the adipose tissue. Furthermore, the lipolytic effect of locally released NA is not inhibited by acidosis, in contrast to the findings with circulating NA. This difference cannot to any major extent be explained by increased transmittor release during acidosis.
Change in Active State during the Staircase Phenomenon of Human Muscle
Authors: Rosenfalck Poul
Published: December 2008

The aim of this study was to determine the active state curve of normal and potentiated isometric twitch contractions of human muscle. Using Hill's (1949) two‐component model of muscle the active state curve was calculated from the course of isometric tension development. It was assumed that the force‐extension diagram of the series elasticity was exponential. Hill's characteristic relation between force and shortening velocity was modified to include the rise and decline in active state. Data from 4 m. adductor pollicis and 3 platysmas were analysed. In normal twitches active state had a maximum of about 0.5 Po occurring at one fifth to one third of the time to peak force, P0 denoting the isometric tetanic force. In potentiated twitches maximum intensities of 0.70‐0.85 P0 and of 0.8‐1.0 P0 were obtained in m. adductor pollicis and platysma respectively. In m. adductor pollicis the intensification of activation was most pronounced around the maximum of the curve.
Substrate Activation and Product Inhibition of LDH Activity in Human Skeletal Muscle
Authors: Karlsson Jan , Hulten Bodil , Sjodin Bertil
Published: December 2008

Substrate activation and product inhibition have been studied on LDH activity in both directions in human skeletal muscle. Km for the forward and backward reactions for pyruvate and lactate were found to be 0.8 × 10‐4 and 0.9 times 10‐2 M, respectively. For increases in concentrations of NAD and NADH the LDH activity was found to increase curvilinearly and no Km value could be obtained. Inhibition of the LDH activity corresponding to 50 % of Vmax was obtained for the forward reaction with a lactate concentration equal to 0.3 × 10‐2 M and for the backward reaction (pyruvate) the corresponding value was 1.0 X10‐4 M. With concentrations of lactate and pyruvate approximately corresponding to maximal values observed in skeletal muscle with exercise, the inhibition of LDH activity in both directions was equal to or more than 70 % of Vmax. It is concluded that in an in vitro system concentrations of lactate and pyruvate similar to what are observed under physiological conditions in human skeletal muscles will induce a significant product inhibition on LDH activity obtained from human skeletal muscles in both reaction directions. It seems reasonable to assume that the present in vitro findings might reflect functions operating in an in situ system. Thus it is possible that the products of the LDH catalysed reactions (lactate or pyruvate) might have a regulatory effect on the anaerobic glycolysis as well as the oxidation of lactate in human skeletal muscle.