摘要:

AbstractThe cerebral blood flow and, in some rats, the cerebral rate of oxygen consumption were measured in three groups of male rats. Fractionation of radioisotope‐labeled microspheres was used to measure regional cerebral blood flow in four parts of the rat brain. The arterial and cerebral venous concentrations of radioactive xenon during desaturation were used to measure the blood flow and oxygen consumption of cortex when venous blood was collected from the superior sagittal sinus, or of whole brain when the transverse sinus was sampled. The regional cerebral blood flow measured with microspheres had a large standard error reflecting the technical difficulty of this method. The cerebral blood flow measured with xenon was higher when venous blood was sampled from the superior sagittal sinus than when sampled from the transverse sinus, but cerebral oxygen consumption rates were similar. The difference reflects the greater trauma involved in the superior sagittal approach and possible extracerebral contamination present in the transverse sinus approac

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05950.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAltered catecholamine receptor sites within the striatum have been proposed to be an important pathogenetic factor in hepatic and porto‐systemic encephalopathy and coma. The unstimulated, fluoride‐, norepinephrine‐ and dopamine‐stimulated adenylate cyclase activity were measured in the corpus striatum of rats with a four weeks old end‐to‐side porto‐caval anastomosis. There was no difference in unstimulated, fluoride‐ or hormone‐stimulated adenylate cyclase activity between porto‐caval shunted and sham‐operated rats. Thein vitrodose‐response curves of norepinephrine and dopamine were similar in both groups of animals. Half‐maximum and maximum stimulation were achieved in shunted and sham‐operated rats by identical concentrations of norepinephrine and dopamine, respectively. The results indicate that neither changes in unstimulated adenylate cyclase activity nor changes in the response of adenylate cyclase activity to fluoride, norepinephrine and dopamine had developed in th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05951.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Abstract7 young, healthy, male subjects performed exercise on bicycle ergometers in two 20 min periods with an interval of 1 h. The first 10 min of each 20 min period consisted of arm exercise (38–62% of Vdot;o2max for arm exercise) or leg exercise (58–78% of Vdot;o2max for leg exercise). During the last 10 min the subjects performed combined arm and leg exercise (71–83% of Vdot;o2max for this type of exercise). The following variables were measured during each type of exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow (only during leg exercise and combined exercise), arterio‐venous concentration differences for O2and lactate at the levels of the axillary and the external iliac vessels.Superimposing a sufficiently strenuous arm exercise (oxygen uptake for arm exercise 40% of oxygen uptake for combined exercise) on leg exercise caused a reduction in blood flow and oxygen uptake in the exercising legs with unchanged mean arterial blood pressure. Superimposing leg exercise on arm exercise caused a decrease in mean arterial blood pressure and an increased axillary arterio‐venous oxygen difference. These findings indicate that the oxygen supply to one large group of exercising muscles may be limited by vasoconstriction or by a fall in arterial pressure, when another large group of muscles is exercising simul

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05952.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractPlasma glucagon concentration was determined by radioimmunoassay during fasting and following teasing and sham feeding. Teasing and sham feeding for 1–10 min raised the plasma glucagon concentration which then within a short period of time returned to the basal level. Atropinization (0.2 mg/kg) almost abolished the glucagon response to 10 min of sham feeding. Glucose concentration was slightly elevated in response to 10 min of sham feeding. The results show that physiological stimulation that is induced by the smell. sight and taste of food releases glucagon in the dog. The release is mediated by a cholinergic mechanis

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05953.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of i.v. infusion of noradrenaline on activity in the renal sympathetic nerve was studied in rabbits anesthetized with chloralose and urethane. Noradrenaline (3–8 μg/kg·min) initially increased mean arterial pressure 20–40 mmHg and consequently reduced renal nerve activity. However, studies over a wide range of pressures—obtained by changing the blood volume, revealed that noradrenaline after a few minutes had induced a pressure‐independent reduction of sympathetic discharge. The effect disappeared with baroreceptor denervation. An unchanged relationship between arterial pressure and integrated activity in the whole left aortic nerve (which is largely a measure of activity in A fibres) suggested that the sympathetic depression was due to excitation of aortic nerve C fibres. This conclusion was supported by studies of sympathetic responses to selective stimulation of aortic nerve A and C fibres at equal pressures before and during infusion of noradrenaline. Compared to the reflex activity from A fibres, C fibre stimulation was invariably less effective in suppressing renal nerve activity during the infusion. Our studies indicate that noradrenaline may effect a negative feedback control of sympathetic discharge through activation of baroreceptor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05954.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractMast cell granules free of a surrounding membrane were isolated from water‐lysed rat peritoneal and thoracic mast cells by differential centrifugation. The granules were depleted of their histamine by suspension in 10 mM sodium phosphate buffer and the sodium‐charged granules then converted into the “hydrogen form” by repeated washing in slightly acid deionized water. The cation exchanger properties of the mast cell granules were investigated by testing the applicability of the Rothmund‐Kornfeld equation for cation exchangers to the binding of Na+and Hi+ions to granule sites. The results lend further support to the view that the mast cell granule acts as a cation exchanger with the exchanger function localized to protein carboxyls in the protein‐heparin complex of the gra

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05955.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractTo evaluate the effect of extreme endurance training on muscle fibre composition and activities of oxidative enzymes in different fibre types biopsies were taken from vastus lateralis, gastrocnemius and deltoideus of elite orienteers. Comparisons were made between the (trained) leg muscles and the (relatively untrained) arm muscles, and with leg muscles of 16–18 years old boys. The orienteers had the same percentage type I fibres in vastus lateralis and gastrocnemius as in deltoideus, but higher percentage type I fibres in vastus lateralis compared with the controls. The similarity between trained and untrained muscle in the orienteers suggests that training had not caused the high percentage type I fibres which rather might be the result of selection of individuals with the best prerequisites for high oxidative capacity. However, the distribution of type II subgroups in the leg muscles of the orienteers differed from both their own deltoideus and leg muscles of the controls, the relationship IIA/IIB being altered in favour of the more oxidative IIA. The leg muscles of the orienteers also showed an increased occurrence of the normally rare IIC fibre. These latter findings point at the possibility of a training induced alteration in the subgroup pattern. Unlike in the controls there was no significant difference in succinate dehydrogenase activity, measured in single fibres, between type I and II fibres in gastrocnemius of the orienteers. Thus, type II fibres have the ability metabolically to adapt to high oxidative demands. This might to some extent be mediated by a conversion from IIB to IIA for

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05956.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of the oestrogens, oestradiol and oestriol, on plasma albumin dynamics in the uterus was studied in mice. A double isotope technique with125I‐ and131I‐labelled human serum albumin was used. The optimum conditions to measure the extravascular accumulation of albumin were to use one labelled albumin as “permeability marker” (30 min circulation time) the other as plasma volume indicator (3 min circulation time). The oestrogens increased the extravascular accumulation of labelled albumin in the uterus but not in diaphragm or heart muscle. The accumulation was maximal after 4 h (75% higher than in controls) and was significant as early as 2 h after oestrogen administration. It cannot be decided whether the increase in labelled albumin accumulation was due to an increase in permeability and/or to an increase in the total surface area of perfused capi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05957.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractCapillary permeability in cutaneous tissue for57Co‐cyanocobalamin (57Co‐B12) was determined by the single injection, external registration method. The capillary diffusion capacity, CDC (the permeability‐surface area product, PS) was 2.3 ml/100 g·min. Capillary extraction was 0.48 at a plasma flow of 4.1 ml/ 100 g·min. Results were compared to51Cr‐EDTA data from a previous study with identical method and preparation. As CDC(51Cr‐EDTA)/CDC(51Co‐B12) was 1.61 and as D(51Cr‐EDTA)/D(51Co‐B12), the ratio between the free diffusion coefficients in water at 37deg;C, was 1.79 it is concluded that restricted diffusion does not occur in cutaneous tissue for57Co‐B12 as compared to51Cr‐EDTA,i.e.51Cr‐EDTA and57Co‐B12 diffuse across the capillary membrane of cutaneous tissue at rates proportional to their respective free diffusion coefficients in water. The Pappenheimer equivalent pore radius estimate of 30 Å and the Karnovsky interendothelial 40 Å slit width are both defective in explaining the experimental data. The transendothelial patent channel system of fused vesicles (Simionescu, Simionescu and Palade 1975) is a possible structural equivalent for the present findings. The results support the hypothesis that capillaries of continuous type exhibit similar permeation characteristics regardless of the tissu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05958.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractTwo female reindeer were hydrated by administration of (10% of b.wt.) water into the rumen. The diuretic response was very fast and strong but the urea and electrolyte excretion were little affected. Dehydration was carried out by not giving the reindeer water for 48 h. This water deprivation caused a loss of up to 20% of their body weight. The urine osmolality did not exceed 840 mosm/kg H2O, although the plasma osmolality rose from 300 to 346 and 368 mosm/kg H2O respectively. The plasma and urine urea concentrations were elevated during dehydration, while the urine urea excretion did not increase. Urine sodium concentration did not increase. When the urine flow rate, after two days of water deprivation, decreased to half of the original, the urine Na+concentration, instead of increasing, went down to half of the original. So did the potassium excretion. When ADH was injected intravenously into hydrated animals a dose of 30 mU of ADH was needed to induce antidiuresis or increased excretion of potassium. The resistance to ADH and the low relative thickness of the medulla confirm the limited capacity of reindeer kidney to concentrate urine or to excrete a solute load. On the other hand, reindeer is able rapidly to excrete surplus water without affecting the electrolyte or nitrogen balance.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1977.tb05959.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY