bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anaphylatoxin‐induced shock and two patterns of anaphylactic shock: Hemodynamics and mediators*
Authors: Pavek K. , Piper Priscilla J. , Smedegârd G. 
Published: December 2008

AbstractIn the dog, différent cardiorespiratory reactions were identified in two types of anaphylactic shock and in C5a‐AT (anaphylatoxin)‐induced shock. AU three types had in common a portai blood pooling with conséquent decrease in the venous return, cardiac output, and arterial pressure. In anaphylaxis (a) of the first type, at a low titer of hemagglutinating antibodies, the latent period was 68 s and heart and lung function was unchanged. In the second type, at high titer, the latency was 19 s and pulmonary hypertension and decreased heart contractility occurred. After AT injection pulmonary hypertension appeared with tachypnea and unchanged heart function. Tachyphylaxis, but not cross‐over tachyphylaxis against the anaphylactic agent and AT was observed in dogs and isolated guinea pig lungs. AT induced a tran‐sient release and a. a prolonged release of histamine, prostaglandins (PGs), and thromboxane A2 and endoperoxides from guinea pig lungs. SRS‐A was released only in a. Indomethacin inhibited AT‐induced release of PGs in guinea‐pig lungs and AT‐induced hypotension in the dog though it did not prevent the drop in cardiac output. Thèse model studies suggest that différent patterns of clinical a. can occur, depending on the type of antibodies and/or mediators involved.
Pregnancy‐induced alterations in the turnover rate of3H‐noradrenaline formed from3H‐tyrosine in guinea‐pig uterus
Authors: THORBERT G. , ALM P. , OWMAN CH. , SJÖBERG N.‐O. 
Published: December 2008

AbstractThe rate of noradrenaline (NA) turnover in the non‐pregnant and pregnant guinea‐pig uterus was determined after the administration of the labelled precursor, tyrosine. Endogenous NA was determined fluori‐metrically. In non‐pregnant animals the turnover of3H‐NA was slower in the uterine horns (t½= 10 h) and cervix (t½= 9 h) than in the reference organ, heart (t½= 6 h). During pregnancy (60–65 dayspost coitum)endogenous NA in the heart increased in pace with tissue weight gain; yet, in the uterus there was a drastic reduction, down to zero levels.3H‐NA turnover increased significantly in the cervix, no3H‐NA formation remained in the uterine horn (a situation resembling that following 6‐hydroxydopamine induced sympathectomy of non‐pregnant animals), and the turnover was unaltered in the heart. The observations confirm the general idea, illustrated by the results in the heart, of a functional adaptation with a constant neuron‐target relationship during increased physiological demands. They also confirm that a very peculiar and complex neuron‐target relationship develops in the uterus during pregnancy‐involving functional and structural denervation of the adrenergic nerve plexus in the uterine horn, whereas an increased activation might explain the changes in neuronal NA and its turnover in the cervix.
Effects of 4‐aminopyridine on the excitation‐contraction coupling in frog and rat skeletal muscle
Authors: KHAN A. R. , EDMAN K. A. P. 
Published: December 2008

AbstractThe effects of 4‐aminopyridine (4‐AP) were studied on isolated single muscle fibres of the frog and toe muscles of the rat. In both muscle preparations, 4‐AP potentiated the twitch amplitude without significantly affecting the tetanus response. There was an increase of the time to peak tension and, in frog muscle, an increased time to half relaxation. 4‐AP produced no change of the resting membrane potential. The rate of decay and, hence, the total duration of the action potential were markedly prolonged. 4‐AP did not induce contractures by itself nor did it affect the contracture induced by caffeine. The mechanical threshold was determined by measuring the contracture response to various degrees of depolarization by potassium. This threshold was not affected by 4‐AP. Twitch potentiation by 4‐AP was independent of the extracellular calcium concentration. It is concluded that 4‐AP potentiates the twitch response by increasing the release of activator calcium into the myofibrillar space by prolongation of the action potential. In addition, there may be a more direct inhibitory action of 4‐AP on the calcium re‐uptake by the sarcoplasmic reticulum in frog muscle.
Studies on the enzymatic blood‐brain barrier: Quantitative measurements of DOPA decarboxylase in the wall of microvessels as related to the parenchyma in various CNS regions
Authors: HARDEBO J. E. , FALCK B. , OWMAN CH. , ROSENGREN E. 
Published: December 2008

AbstractThe presence of DOPA decarboxylase in cerebral microvessels (capillaries and venules) impedes the passage of circulating amine precursors into the brain. The relative amount of DOPA decarboxylase in this trapping mechanism as compared to the parenchymaper sewas estimated in various CNS regions, measuring the formation of dopamine from L‐DOPAin vitroorin vivoin two experimental models on rats and rabbits: (1) On the basis of the treatment with a peripheral decarboxylase inhibitor (carbidopa, which inhibits also microvascular DOPA decarboxylase in the CNS) it could be calculated that the enzyme in the microvessels of the caudate nucleus (rich in catecholamine nerve terminals), cerebellum (poor in catecholamine nerves), and spinal cord comprised 25, 91 and 79 per cent, respectively, of the total enzyme activity. (2) Measurement of dopamine formation in the spinal cord following transection at the midthoracic level (which causes degeneration of the catecholamine neurons caudal to the lesion since they are all descending) indicated that a similar fraction as found in the carbidopa model, 71 per cent, of the total tissue decarboxylase activity resided in the microvessel walls. The results show that a considerable portion of tissue decarboxylase in the CNS is present in the microvessel walls, where it represents part of an enzymatic blood‐brain barrier mechanism.
Vascular anatomy and tissue osmolality in the filiform and fungiform papillae of the cat's tongue
Authors: HALLBÄCK DAN‐AXEL , JODAL MATS , LUNDOREN OVE 
Published: December 2008

AbstractThe vascular anatomy of the filiform and fungiform papillae of the feline tongue was studied by i.a. injection of India ink. Vascular loops of various appearances were found in the types of papillae studied, i.e. the large and the small filiform papillae and the fungiform ones. Such hairpin loops may function as counter‐current exchangers and to test this hypothesis tissue osmolality was determined in the papillae, while exposing them to various isotonic electrolyte solutions. The large filiform papillae with a vascular arrangement similar to that of intestinal villi exhibited a marked osmolar gradient from tip to base when exposed to a solution containing both glucose and sodium. If sodium and/or glucose was excluded from the solution, tissue osmolality was significantly decreased. This was also the case when the chloride ions of the solution was substituted with sulphate. The small filiform papillae are only provided with one or a few capillary loops. They exhibited a less marked osmolar gradient than the large ones and none of the different electrolyte solutions decreased the gradient. In the fungiform papillae a tissue hyperosmolality at the tip was also demonstrated. It is proposed that the papillary epithelium is provided with active transport mechanism(s) and that the papillary vessels function as countercurrent multipliers. The functional importance of these mechanisms are tentatively discussed.
Effect of splenic nerve stimulation on the contents of noradrenaline, ATP and sulphomucopolysaccharides in noradrenergic vesicle fractions from the cat spleen
Authors: BLASCHKE E. , UVNÄS B. 
Published: December 2008

AbstractIn order to assess the effect of splenic nerve stimulation on the contents of noradrenaline, ATP and36S‐la belled compounds in noradrenergic vesicles from the spleen, experiments were carried out on the cat spleenin situ, its frontal portion being used as control. Particulate fractions containing noradrenergic vesicles were isolated on Ficol! gradient centrifugation of homogenates from both portions of the spleen. The cats hstReceived phenoxybenzamine (10 mg/kg) and imipramine (5 mg/kg) to inhibit the contractive response of the spleen to nerve stimulation and the reuptake of noradrenaline (NA) into nerve terminals. Administration of the drugs did not significantly affect the levels of NA, ATP and36S (presumably in sulphomucopolysaccarides, SMPSs). In response to prolonged stimulation of the splenic nerve a significant loss of NA from noradrenergic vesicles occurred, whereas levels of ATP and36S‐labelled compounds remained unchanged. The results indicate that a discharge of NA in response to nerve stimulation is not accompanied by simultaneous discharge of ATP and SMPSs.
Formation of cadaverine in the pregnant rat
Authors: ANDERSSON ANNE‐CHARLOTTE , HENNINGSSON STIG , ROSENGREN ELSA 
Published: December 2008

AbstractThe formation as well as the content of cadaverine were determined in different tissues of pregnant and non‐pregnant rats. The placenta and ovary were most potent in the ability to form cadaverine. To our knowledge this is the first report of an in vitro formation of cadaverine linked to a normal physiological process, i.e. pregnancy. The highest concentration of cadaverine was found in the placenta and ovary of the pregnant rat. Treatment with aminoguanidine generally elevated the content of cadaverine, indicating a role of diamine oxidase as a regulator of diamine content.
Correlation between fluid reabsorption and proximal tubule ultrastructure during development of the rat kidney
Authors: APERIA ANITA , LARSSON LARS 
Published: December 2008

AbstractParallel functional and ultrastructural studies were performed in maturing rats in order to elucidate factors determining the development of proximal tubular fluid reabsorption. Three groups of hydropenic animals, which were 22 to 24, 28 to 32 and 40 to 45 days old, were studied. Nephron function was evaluated at the single nephron level by micropuncture technique. The ultrastructure of the developing proximal tubules was analysed by morphometric techniques following fixation of single nephrons. Kidney weight, proximal convoluted tubule length and diameter increased during postnatal development. SNGFR increased from 2.98 to 8.57 and to 20.5 nl/min in respective group of rats whereas proximal tubular fluid reabsorption Jv (a) increased from 0.15 to 0.22 and 0.34 μm3μm_2‐s _1. Parallel to the functional development the relative area of lateral and basal cell membrane increased, resulting in a constant relationship between net fluid reabsorption and the lateral and basal cell membrane area during the fourth postnatal week and then only a slight increase in this relation during the further development. The results suggest that net fluid transport during hydropenia is determined by the amount of available lateral and basal cell membranes where the transporting enzyme for sodium is located.
Nervous control of pancreatic exocrine secretion in pigs
Authors: HOLST JENS J. , De MUCKADELL OVE B. SCHAFFALITZKY , FAHRENKRUG JAN 
Published: December 2008

AbstractThe pancreatic secretion of fluid, bicarbonate and protein in response to electrical stimulation of the vagus and splanchnic nerves, to exogenous and endogenous secretin and to various pharmacological agents was studied in anesthetized young pigs (21 kg). Vagal stimulation increased flow, bicarbonate output and protein output in a frequency dependent manner; the half maximal effective frequency was 2–4 Hz and the maximal effective frequency 12 Hz. The secretory response to vagal stimulation was potentiated by physiological elevations of the arterial concentration of secretin brought about by injection of secretin or by acidification of the duodenal bulb. Simultaneous stimulation of the splanchnic nerves strongly inhibited the response to vagal stimulation; splanchnic nerve stimulation alone had no demonstrable effect. The flow and bicarbonate response to vagal stimulation was unaffected by atropine, but abolished by hexa‐methonium. Protein output was strongly inhibited by both agents. The response to intraarterial infusion of acetylcholine resembled that elicited by vagal stimulation but it was smaller and it was completely abolished by atropine and unaffected by hexamethonium. Alpha‐ and beta‐adrenergic blockade stimulated rather than inhibited the secretory response to vagal stimulation. The portal vein plasma concentration of secretin was not affected by vagal stimulation. The results indicate that the protein response, and the flow and bicarbonate response to vagal stimulation are not brought about by the same mechanism. An increased release of secretin is not involved. Peptidergic (VIP‐containing) nerves may contribute.
Decline and disappearance of taste response after interruption of the chorda tympani proper nerve of the rat
Authors: HELLEKANT G. , GOPAL V. , NINOMIYA Y. 
Published: December 2008

AbstractThe response amplitude in the chorda tympani proper nerve of rats to taste stimulation has been studied at different times after interruption of the nerve in the middle ear. The results show that the response in the nerve declined and disappeared completely within 15 h after the nerve was interrupted. As a first sign of deteriorating function a stage of hypersensitivity was observed. Results obtained during applications of local anesthetic or colchicine and section at different distances from the tongue indicate that the decreased response was the result of an interruption of axoplasmic flow from the nerve cell bodies in the geniculate ganglion to the taste buds.
In mice aggressive behaviour provokes vast increase in plasma renin concentration, causing only slight, if any, increase in blood pressure
Authors: BING JENS , POULSEN KNUD 
Published: December 2008

AbstractIn mice aggressive behaviour causes a vast release of renin, which can result in about 600‐fold increase in plasma renin concentration, reaching 6 Goldblatt Units, corresponding to 15μg renin per ml. This increase is mainly due to release of submaxillary renin, but there is also a significantly increased renal renin release. The degree of renin release is influenced by the duration of the aggression and by previous contact with other mice. Contrasting with the vast increase in plasma renin the blood pressure is normal or only moderately increased. This disproportion is not due to the depletion of renin substrate, caused by the increased renin, as shown by the increased calculated renin activity, as well as by decrease in blood pressure elicited by blockade of the renin system. Nor is the disproportion due to change in the sensitivity of the vessels to angiotensin II, the cause of this lack of tachyphylaxis being unknown. By way of exclusion the lack of pronounced increase in blood pressure can be explained by homeostatic function of the cardiovascular reflexes, which may also account for the fact that the pressor response after injection of pure submaxillary renin is only short, contrasting with a prolonged marked increase in plasma renin concentration.
Gastric acid secretion and water balance in the marine teleost Gadus morhua.
Authors: HOLSTEIN BJÖRN 
Published: December 2008

AbstractGastric acid secretion was measured in unanaesthetized codfish surgically equipped with a catheter draining the stomach. The pylorus was ligated. Without perfusion of the intestine, or during perfusion with pure sea water (100% SW) or slightly diluted (67%) SW, gastric acid secretion was low (< 10 μmol H+/kg‐h) and the fishes became dehydrated during the experiment. Perfusion of the intestine with 50% or 33% SW enabled the fishes to compensate for the water loss to the environment and greatly enhanced gastric acid secretion. Acid secretion was elevated also in fishes in which the dehydration was prevented by an intramuscular infusion of saline. Perfusion of the intestine (8.5 ml/h) decreased the hourly effluent volume (‘drinking rate’) from the stomach to almost zero within 2 h. The effect was independent of the degree of dilution of the perfusing SW, but was less pronounced when the perfusion rate was lowered. Intra‐muscular saline also depressed ‘drinking rate’. The acid secretion prevailing during perfusion of the intestine with SW at a dilution preventing dehydration–suggested to represent the basal acid secretion of the codfish– was inhibited by atropine, hexamethonium, and metiamide.
Synthesis of3H‐acetylcholine in the rabbit lacrimal gland and its release by electrical field stimulation
Authors: WIKBERG JARL E. S. 
Published: December 2008

AbstractElectrical field stimulation was applied to the rabbit lacrimal gland during incubationin vitrowith3H‐choline, after which the efflux of tritiated metabolites was studied. In the presence of physostigmine3H‐acetylcholine was released into the incubation medium when the gland was stimulated electrically. The identity of the3H‐acetylcholine synthesized by the preparation was established by its identical ion exchange chromatographic properties to native acetylcholine. The tissue contents of3H‐acetylcholine and3H‐choline were 14.4 and 3.6%, respectively, of the total activities found in the gland. This study demonstrates that the rabbit lacrimal gland is innervated cholinergically. It is suggested that the method developed might be of value for studying effects of drugs on cholinergic neurotransmission in this organ.
PCO2 of the proximal tubular fluid and the efferent arteriolar blood in the rat kidney
Authors: Sohtell Morgan 
Published: December 2008

AbstractRecordings in vivo of the carbon dioxide tension of the proximal tubular fluid and of the efferent arteriolar blood were performed with PCO2 microelectrodes in the rat kidney. The buffer lines of the efferent arteriolar blood and systemic arterial blood were determined with an ultramicro equilibration system and the acid‐base status of the systemic arterial blood was measured. The intratubular PCO2 was significantly higher than the PCO2 of the arterial blood, and the PCO2 of the efferent arteriolar blood was significantly lower than that of the arterial blood. The buffer capacity was higher and the bicarbonate concentration slightly lower for the efferent arteriolar blood than for the arterial blood. It is concluded that a PCO2 difference exists across the tubular wall and that the high intratubular PCO2 favours a chemical equilibrium of the carbonic acid‐bicarbonate system in the proximal tubular fluid. It is supposed that the slightly lowered bicarbonate concentration in the efferent arteriolar blood is an effect of the glomerular ultrafiltration process.
CO2 along the proximal tubules in the rat kidney
Authors: Sohtell Morgan 
Published: December 2008

AbstractThe proximal intratubular pH of the rat kidney was measured in vivo with an antimony electrode system. PCO2 and bicarbonate concentration of the proximal tubular fluid were determined with an ultramicro equilibration system. The tubular fluid to plasma inulin concentration ratio was evaluated by a microscope fluorometric method. The acid‐base parameters and the inulin concentrations were determined under control conditions and during acetazolamide treatment. The intratubular PCO2., was higher than the PCO2 of the systemic arterial blood under control conditions and the difference in PCO2 was increased during acetazolamide treatment. In acetazolamide treated rats the rate of fractional bicarbonate reabsorption was decreased in the early part of the proximal tubule, while it was of about the same in the middle and late parts as compared with control rats. The total bicarbonate reabsorption in the proximal tubule was reduced by 50% due to the carbonic anhydrase inhibition. It seems possible that the bicarbonate is still reabsorbed as CO2 after carbonic anhydrase inhibition, as hydrogen ion secretion is not totally stopped by this treatment. The increase in intratubular PCO2 after acetazolamide treatment is assumed to be due to an inhibition of the carbonic anhydrase facilitating effect on outward diffusion of CO2 from the tubular lumen across the cell wall.
Interrelationships between skeletal muscle adaptations and performance as studied by detraining and retraining
Authors: Houston Michael E. , Bentzen Henning , Larsen Henrik 
Published: December 2008

AbstractThe effects of 15 days of detraining and 15 days of retraining were studied in 6 well‐trained runners. Detraining resulted in significant decreases in the mean activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) of 24 % and 13 %, respectively, but no significant increases in these enzyme activities occurred with retraining. Maximal oxygen uptake (VO2 max) decreased by 4% with detraining (p < 0.05), and increased by a similar amount with retraining. Performance time in an intense submaximal run decreased by 25% (p < 0.05) with inactivity, but still averaged 9% below the initial level after retraining. Maximal heart rate and peak heart rate during the performance run were higher after detraining by 4 and 9 beats per min, respectively (p < 0.05). With retraining, these heart rate values were decreased by 7 and 9 beats per min (p < 0.05). Blood lactate concentrations after the VO2 max and performance run were approximately 20% lower after detraining and retraining (p < 0.05). Muscle fibre areas for three subjects tended to be larger in biopsy samples taken after detraining and retraining. These data suggest that even short periods of detraining result in significant changes in indices of physiological capacity and function in subjects near their upper limit of adaptation, and that a longer period of retraining is necessary for muscle to re‐adapt to its original trained state.
Transcapillary passage of albumin, effects of tissue cooling and of increases in filtration and plasma colloid osmotic pressure
Authors: Rippe Bengt , Kamiva Akira , Folkow Björn 
Published: December 2008

Abstract‘Initial’ clearance of radiolabeled serum albumin was measured in the perfused, maximally vasodilated muscle vascular bed of rat hindquarters during tissue cooling, during increases in filtration and during changes in serum colloid osmotic pressure. Albumin clearance during ordinary serum perfusion at iso‐gravimetry amounted to 0.03 ml/min x 100 g, increasing linearly with filtration rate to some 0.07 ml/minx 100 g at 0.5 ml/minx 100 g of filtration. During cooling from 36°C to 14°C both CFC and initial albumin clearance at isogravimetry decreased some 40%, in due proportion to the increased viscosity of the fluid. Increases of the colloid osmotic pressure of the perfusate correspondingly increased both the isogravimetric capillary pressure and ‘initial’ albumin clearance during isogravimetry. – It is concluded that even during isogravimetry the transmicrovascular albumin passage is to about 70 per cent due to filtration, and only some 30 per cent of transport at ordinary serum colloid osmotic pressures takes place by diffusion, both events presumably via ‘large pores’. There was no evidence that transendothelial vesicular transport should to any significant extent contribute to the passage of albumin from vessels to tissue.