摘要:

AbstractApproximately isopnoeic conditions (VE=40 1/min) were achieved by the inhalation of asphyxial gas mixtures (PA1O260 torr, PA1CO240–45 torr) in normothermia and after a rise in rectal temperature of 1.6°C had been induced by a heated flying suit. Arterial chemoreceptor drive was transiently reduced by either isocapnic removal of hypoxia (type (1) tests: two breaths of CO2in O2) or simultaneous withdrawal of both hypercapnia and hypoxia (type (2) tests: two breaths of O2). 8–13 tests of each type were performed at both temperature conditions in 6 expts. on 4 healthy human subjects. Expired volume, total breath duration and inspiralory time were recorded, and minute ventilation and expiratory time subsequently computed breath by breath. In hyperthermia the steady‐state ventilation of 40 1/min (at a relatively higher respiratory frequency and a correspondingly lower tidal volume) was achieved at a PA1CO2which was 5 torr lower than in normothermia. Ventilation decreased significantly in all tests. Tested with a 3‐way analysis of variance significant differences between the ventilatory responses at the two temperature conditions, and between the two test types were found. The rate of change of ventilation was greater in hyperthermia than in normothermia, and also greater in type (2) tests than in type (1) tests. Since isopnoeic conditions existed prior to the tests, this implies that the arterial chemoreceptor contribution to the total ventilatory drive is increased in hyperthermia. In type (2) tests a significant lengthening of expiratory time was observed in the first test breath. This finding confirms the effect in man of changes in airway PCO2on lung stretch receptor d

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06072.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractHistamine release induced by X537A from isolated rat mast cells was dependent on the presence of sodium or potassium but not on calcium in the incubation medium. The rate of release was faster in potassium than in sodium, but the final release was the same after prolonged incubation. Extracellular calcium as well as metabolic inhibitors depressed the rate of release induced by X537A. Pretreatment of mast cells with either EDTA or the ionophore A23187 in the absence of extracellular calcium did not influence subsequent release induced by X537A. The findings of release at 45°C and lack of release at 0°C distinguish the mechanism of action of X537A from calcium‐and energy‐dependent releasing agents like compound 48/80 and A23187 on the one hand and the simple lytic action of decylamine on the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06073.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractNine anesthetized dogs were provided with acute common duct fistulas after exclusion of the gallbladder. Synthetic Substance P was administered as caval infusions in a dosage of 0.5–20 ng × kg‐1× min‐1, duration 10 min. The output of hepatic bile, sodium and amylase decreased during infusion by 40–52 per cent at the highest doses. After termination of infusion all 3 parameters increased by 19–60 per cent above the basal level. The biliary concentration of sodium was constant, while that of amylase increased during infusion. The responses were dose‐related. The anticholeresis induced by Substance P might be due to inhibition of the canalicular bile fraction, which presumably is mediated by active sodium transport and independent of bile s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06074.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA method for measuring cAMP in frog skin epithelium was developed. The epithelia were isolated after collagenase‐treatment. cAMP was extracted by boiling water and the extract was purified on dry AI2O3. The change with time of the cAMP level after addition of arginine vasotocin (AVT) was studied. The hormone caused a rapid increase in cAMP level with a maximum after 3–5 min, whereafter the cAMP level declined. Incubation with AVT made the epithelia refractory to a second dose of AVT, which indicates that the decline in cAMP level was caused by a feedback mechanism and not by inactivation of the hormone. cAMP appeared evenly distributed in all cell‐layers of the epithelia both before and after stimulation with AVT. Theophylline caused a rapid increase in the cAMP level, which remained elevated for at least 45 min. Addition of the ionophore A23187 or of filipin had no effect on the cAMP level. However, in the presence of theophylline, A23187 enhanced the cAMP level, whereas filipin had no effect. Therefore the involvement of cAMP in the action of A23187 has to be consi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06075.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe maturation of circulating red blood cells (RBC) in salmon (Salmo salarL.) has been studied. A developmental RBC series of 6 classes based on morphological criteria was proposed. After a single dose of iron (55Fe) given to 5–6 months old salmon the incorporation of radioactivity in maturing RBC was followed by autoradiography on blood smears. The relative distribution of labelled RBC between the 6 classes in specimens taken 15, 20, 41, and 52 days after the injection of iron showed that the RBC matured along the proposed series. The projected area of the RBC increased by 100% during the maturation. This RBC growth was caused by an elongation of the RBC. Thus the ratio between short and long axes of the RBC decreased with maturation and can be used as a measure of the degree of maturation. The uptake of radioactive iron measured as grain count per RBC or per projected area of the RBC increased during the maturation in classes II‐IV. Radioactive iron was not incorporated by mature RBC. The maturation time from class I to class VI was shorter than 41 days. RBC iron bound to non‐haemoglobin proteins as a possible restriction in estimations of the haemoglobin concentrations of developing RBC is disc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06076.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effects of insulin on bile flow and composition were examined in fasting, chloralose‐anesthetized cats. Insulin in doses from 0.01 to 2.00 U/kg increased bile flow and biliary erythritol clearance without any detectable change in the difference between them; thus insulin presumably had no effect on ductular fluid transport. Continuous infusion of insulin (0.8 U/kg + 0.05 U/kg/min or 0.05 Uykg + 0.002 U/kg/min) increased biliary erythritol clearance by 22%. The increase was caused by a rise in the bile acid‐independent fraction of bile production and accompanied by a parallel increase in the rates of biliary excretion of Na+and Cl‐. When ouabain, 80 μg/kg, was injected intraportally during insulin infusion the erythritol clearance, bile flow and the rates of biliary excretion of Na+and Cl‐were lowered towards but not to their pre‐ insulin levels. The effects of insulin on these parameters were unchanged after atropin or gastrectomy and 2‐Deoxy‐D‐Glucose was without effect on bile production. The results indicate that administration of insulin affects bile formation by stimulating the active transport of sodium across the cana

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06077.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractCerebral circulatory and metabolic effects of amphetamine sulphate (0.25–25 mg·kg‐1i.v.or 5–10 mg·kg‐1i.p.) were studied in anesthetized, paralyzed and artificially ventilated rats. Cerebral blood flow (CBF) was measured with a modification of the Kety and Schmidt (1948) technique, and oxygen consumption (CMRo2) was calculated from CBF and arteriovenous differences in oxygen content. Regional CBF was evaluated from the uptake of14C‐ethanol. Cortical metabolites were analysed following freezing of tissuein situ.Amphetamine administration gave rise to a marked increase in CBF that was doubled following 0.25 mg·kg‐1and increased 4‐fold following 15 mg·kg‐1. However, such excessive increases in flow were confined to frontoparietal cortical regions, while other cortical or subcortical areas showed more moderate hyperemia. The increase in CBF was unrelated to changes in arterial Pco2, blood pressure, or tissue lactate content. CMRo2increased by 30% to 95% depending on dose and rat strain used. At all doses employed, amphetamine gave rise to glycogenolysis in cerebral cortex but, in animals studied within the first 30 min after 5 mg‐kg‐1, or less, the only other changes were increases in glucose‐6‐phosphate and α‐ketoglutarate concentrations. When the dose was increased to 15 mg·kg‐1, there were moderate increases in lactate concentration and lactate/pyruvate ratio. Sixty min after 5 mg·kg‐1there were increases in tissue concentrations of pyruvate, citric acid cycl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06078.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe extracellular potassium concentration, [K+]e, was measured in the brain cortex of hypo‐, normo‐ and hyperglycemic rats following brain ischemia. The increase in [K+]θin control rats could be characterized by 3 phases: an initial slow rate of rise where the [K+]θrose in 2 min from 3 to 9 mM followed by an abrupt, steep increase to 60 mM within 10 s and finally a slow rise to 80 mM. In the hyper‐ and hypo‐ glycemic rats the same pattern appeared, but there were significant differences in the time course. The duration of the initial phase was approximately doubled in the hyperglycemic and halved in the hypoglycemic group. The [K.+]θat which the steep increase was elicited was 8–10 mM in all groups. It is concluded that the duration of the initial phase is dependent upon available stores of glucose

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06079.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractRegenerative responses were seen in most cells either after cessation of an inward current pulse or during an outward current pulse. Two cell groups were distinguished electrophysiologically. Type I cells showed action potentials with maximum rate of rise of 21.2 ± 9.0 V/sec (mean ± S.D., n= 19), while type II cells generated small graded depolarising responses with maximum rate of rise less than 3 V/s. The resting potentials of type I and II cells were 31.8± 14.9 mV (n = 19) and 41.7 ± 9.8 mV (n = 31), respectively. The steady‐state current/voltage relationship was linear for both cell types when the membrane potential was more negative than — 60 mV. An outward rectification appeared when the membrane potential was more positive than —40 mV. The input resistance was smaller in type I cells (274±212 MΩ, n=19) than in type II cells (1 112 ± 456 MΩ, n=16). Even in Na‐free solution regenerative responses were observed in most cells. When the Ca2+ concentration was increased tenfold to 24 mM, the maximum rate of rise of the off‐response increased from 1.9 ± 0.8 V/s (n = 11) to 5.7 ± 2.12 V/s (n = 5). All‐or‐none action potentials could be evoked in this Ca2+rich solution. Action potentials of similar maximum rate of rise could be evoked after replacing 24 mM Ca2+with isomolar Sr2+. Prolonged action potentials were seen after substitution of Ca2+for Ba2+. It is concluded that action potentials in most anterior pituitary cells have a Ca component, which in type I cells is addit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06080.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe blood flow in the renal portal system of intact hens was characterized by determining the fractional distribution of 15 μm and 50 μm microspheres in this system after injection into a leg vein. Validation tests showed that only 50 μm spheres gave a reliable estimation of this distribution. The blood flow in the coccy‐geomesenteric vein was directed towards the liver in nearly all cases. On the average 44, 47 and 8% of the portal blood from the external iliac vein perfused the ipsilateral kidney, the liver and the lungs, respectively. However, the distribution of portal blood to these organs varied considerably between individuals and changed appreciably within 35 min in half the animals studied. The reason for these variations is not clear. The portal blood from the right and left external iliac veins was asymmetrically distributed in most animals illustrating the importance of local factors in its regulation. Variation was great in the regional distribution of portal blood within the kidney possibly due to local vasoconstriction of portal vessels. Further informatione.g.on the regulation of renal portal blood flow is needed to explain its physiological significance. Microspheres provide a convenient method for such studies. A combination of microsphere and Sperber techniques allows us to determine the renal excretion efficiency of a given subst

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06081.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY