摘要:

AbstractThe role of cyclic AMP for the calorigenic and some other metabolic effects of noradrenaline, 5‐hydroxytryptamine and ACTH has been studied in brown adipose tissue from the rat. Noradrenaline (5×10‐‐6g/ml) increased significantly the cyclic AMP level in brown adipose tissue. All hormones stimulated the O2‐consumption, the lactate and glycerol productions, the FFA release and reduced the ATP content of the tissue. Noradrenaline and 5‐hydroxytryptamine also reduced the glucose‐6‐phosphate content. Noradrenaline increased both the total and the phosphorylase a activity. Addition of cyclic AMP (4.5 × 10‐‐6moles/ml) to the suspension solution increased the O2consumption, the glycerol and lactate productions and the FFA release; the actions were equivalent to those of a noradrenaline concentration of 5×10‐‐8g/ml. In contrast to noradrenaline, cyclic AMP increased the ATP content. Dibutyryl‐cyclic AMP in a ten times lower concentration (5× 10‐‐7mo les/ml) had the same potency in stimulating the O2consumption and FFA‐release as cyclic AMP. Theophylline (4.5×10‐‐3g/ml) stimulated the O2consumption, the glycerol and lactate productions and the FFA release of brown adipose tissue. Theophylline potentiated the effect of cyclic AMP on the O2consumption; and in combination the drugs reduced the ATP and glucose‐6‐phosphate content of the tissue and increased the phosphorylase activity. The magnitude of the metabolic effects was equivalent to the maximal effect of noradrenaline. The increase of AMP produced by cyclic AMP was blocked by theophylline. It is suggested that the studied metabolic effects of noradrenaline is mediated by an increased forma

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04886.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract133Xenon clearance was recorded during maximal vasodilatation in the calf muscles of trained subjects during rest and during heavy rhythmic exercise (contraction about 0.3 sec, relaxation about 0.7 sec) when the subject was tilted from a supine to a “leg down” position. The k‐value for the wash‐out curve, divided by the mean arterial blood pressure at heart level (MABP), was considered to reflect therelativelevels of maximal flow in the two experimental situations. While a shift to “leg down” position during post‐exercise hyperemia did not significantly increase flow through the fully dilated muscle vessels, indicating that they were already maximally distended, the same shift during rhythmic exercise raised the average value of k/MABP approximately 60 per cent above control. This observation is in all probability explained by a marked lowering of mean venous pressure by the “muscle pump” in the dependent legs, despite the huge flow during the heavy rhythmic exercise. This would result in a considerable gain in local perfusion pressure and hence in maxi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04887.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe contents of sodium, potassium, magnesium, chloride, phosphorus and water were determined in the leg and neck muscle of 3– and 14‐day old rats. There were marked differences in electrolyte content between the two age groups and also between the leg and neck muscle of the 3‐day old rat.The results indicate that there is a decrease in the amount of extracellular fluid during maturation. The composition of the intracellular fluid also changes during development insofar as there is a marked decrease in its sodium content.The results indicated that the decrease in intracellular sodium roughly paralleled the rise in membrane potential. It was therefore suggested that the developmental change in the intracellular sodium concentration was secondary to a decrease in the sodium permeability of the muscle cell membrane or to a change in the active transport of sodium across the mem

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04888.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe intracellular distribution of free and potential phospholipases (EC 3.1.1.4) has been studied using isopycnic gradient centrifugation 06 rat pancreatic homogenates. 30 % of the free phopsholipase A2activity was found in the zymogen granules while only 15 % of the total phospholipase A activity was present there. Tryptic digestion increased the phospholipase A activity 20 fold‐an increase only in phospholipase A2activity. The zymogen granules accounted for 30 % of the prophospholipase and revealed a specific activity (activity per mg protein) 3 to 5 times higher than those of the other cell components. The intracellular distribution of prophospholipase is similar to lipas

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04889.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractTo investigate whether vascular smooth muscle of spontaneously hypertensive rats, SHR, (Oka‐moto 1963) displays any hypersensitivity to noradrenaline (NA) as compared to that of normotensive control rats, NCR, helical aortic strips, alternatively portal vein segments, from a SHR and a NCR were mounted in the same organ bath, to which graded NA doses were added. In neither case did the dose‐response curves, expressed as per cent of the maximal responses, reveal any significant difference between SHR and NCR. Thesein vitrostudies are therefore in agreement with the view that the enhanced flow resistance responses, caused by NA (and other vasoconstrictor agents) in SHR as compared with NCR are not the result of any increased sensitivity to NA of the vascular effector cells proper but may rather, as suggested by Folkowet al. (1970), be due to an increased wall/lumen ratio of the SHR resistance vess

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04890.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe rising and falling phases of the active state were analyzed, by means of quick‐release technique, during a series of 4 incompletely fused isometric twitches in single semitendinosus muscle fibres of the frog. The analysis was carried out at different sarcomere lengths within the range 1.7–2.8 μ. The rate of rise of the active state was independent of the sarcomere length. A reduction in fibre length was associated with an earlier onset of the decay of the active state leading to a decrease in duration of the activity at the shorter length. The duration of the active state at 1.9 μ sarcomere spacing was 69 (range: 51–40) per cent of the duration existing at 2.6 μ sarcomere length as determined in 7 different fibres. Movement (active shortening)per se, apart from the change in sarcomere length, affected the kinetics of the active state. An interval of free shortening interposed during an isometric contraction reduced the fibre's capacity to produce tension for the rest of the contraction period without changing the total duration of the mechanical activity substantially. The movement produced a relatively small effect as long as the active state was maximum; the depressant effect became greater and greater, however, the later the movement occurred during the decay phase of the active state. The nature of the length and movement dependence of the active state is discussed in the light of the calcium‐activator mechanism of the excitation‐contract

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04891.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractLiver function was followed by the elimination rate of glyceorol and ethanol and the hepatic uptake of Indocyanine Green. It was demonstrated that a 1° to 2° C reduction of the body temperature or cooling of the portal vein reduced the elimination rate of glycerol and ethanol, as well as the hepatic uptake of Indocyanine Green, about 40 per cent. The experimental findings may be explained by restricted distribution of blood flow in the liver and a corresponding reduction of the functional capacit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04892.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractAfter i.v. injection of heparin (1.6 IU/g b.w.) there was a significant increase of the diamine oxidase (DAO) activity in lymph and blood plasma in rat, guinea‐pig and rabbit. The ratio between lymph and plasma DAO activity was higher in rat and rabbit than in guinea‐pig under basal conditions. This difference was even more pronounced after heparin injection. Withdrawal of mesenteric or thoracic duct lymph from the circulation of the animals was accompanied by a poor response to heparin of the plasma DAO activity in rat and rabbit, whereas the response in the guinea‐pig seemed to be uninfluenced. These results suggest that, in analogy with earlier findings in man, the contribution from lymph to the heparin‐induced DAO response in blood plasma may be significant in the rat and rabbit, but not in the gui

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04893.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractVentilation and heart‐rate responses were recorded continuously and simultaneously during supine leg exercise in six male athletes using positive and negative ramp changes in work load, starting or ending at the fixed minimal and maximal load levels of 250 and 1050 kpm/min. The parameter Tl (“lag time”) is used to define the time by which a ramp response in its stationary condition lags behind the input signal. Three different positive and negative ramp slopes were used, the durations of the ramps being 7, 5 and 3 min (= 114, 160 and 267 kpm min‐2). For ventilation Tl was found to be largely independent of the slope of the ramp and averaged 66 sec. For heart rate, on the other hand, the mean values for Tl obtained from the responses to corresponding positive and negative slopes were 84.0, 56.4 and 38.8 sec, respectively, and proved to be significantly shorter the steeper the ramp. Granted second‐order dynamics of the heart‐rate response to work load, the slope‐dependence of Tl suggests that the share of the shorter time constant becomes larger the steeper the ramp. For the responses of the heart rate to the two steepest ramps, Tl was negatively correlated to work capacity (r= ‐0.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04894.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

AbstractThe changes in csf [HCO3‐] and [lactate]were followed in dogs whose arterial pH, Pco2, and [HCO3‐‐] were kept constant during 6 hrs hypoxia or normoxia. The results confirm that hypoxia causes a lowering of [HCO3‐]csf. We believe it is reasonable to assume that an increased anaerobic glycolysis in the brain is responsible for titrating HCO3‐‐out of csf during isocarbic hypoxia although the lactate concentration in csf increased only about one third as much as the [HCO3‐‐] decreased. The action of hypoxia on [HCO3‐] esf is expressed in terms of its effect on the electrochemical potential difference for HCO3‐‐between mean capillary

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1971.tb04895.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY