摘要:

Abstract10 well trained and 10 untrained subjects worked to complete exhaustion on a bicycle ergometer with work loads averaging 77 (76–87) per cent of their individual maximal aerobic power. Determinations of glycogen used by working muscles (biopsy of lateral portion of the quadriceps femoris muscles) and of combusted carbohydrate (Vo2and RQ) were performed at certain intervals from the start of work to exhaustion. At a combustion rate of about 3 g carbohydrate per minute (RQ around 0.9 or higher) and at average values for glycogen in resting muscle of 1.6 (1.1–2.5)g/100 wet muscle, the effective work time was around 85 min for the untrained and 90 min for the trained subjects. At the end of the exhaustive exercise the glycogen content averaged 0.06 g in the untrained and 0.12 g/100 g wet muscle in the trained subjects. A close relationship between utilized glycogen and combusted carbohydrate was found, and it seems highly probable that at high relative workloads primarily the glycogen stores in the exercising muscles will limit the capacity for prolonged strenuous w

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03719.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThe muscle glycogen content of the quadriceps femoris muscle was determined in 9 healthy subjects with the aid of the needle biopsy technique. The glycogen content could be varied in the individual subjects by instituting different diets after exhaustion of the glycogen store by hard exercise. Thus, the glycogen content after a fat ± protein (P) and a carbohydrate‐rich (C) diet varied maximally from 0.6 g/100g muscle to 4.7 g. In all subjects, the glycogen content after the C diet was higher than the normal range for muscle glycogen, determined after the mixed (M) diet. After each diet period, the subjects worked on a bicycle ergometer at a work load corresponding to 75 per cent of their maximal O2uptake, to complete exhaustion. The average work time was 59, 126 and 189 min after diets P, M and C, and a good correlation was noted between work time and the initial muscle glycogen content. The total carbohydrate utilization during the work periods (54–798 g) was well correlated to the decrease in glycogen content. It is therefore concluded that the glycogen content of the working muscle is a determinant for the capacity to perform long‐term heavy exercise. Moreover, it has been shown that the glycogen content and, consequently, the long‐term work capacity can be appreciably varied by instituting different diets after glycogen d

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03720.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThe net loss of noradrenaline (NA) from bovine splenic nerve granules observed after incubation for 60 min at 20d̀ C in phosphate buffer is reduced in the presence of NA in the incubation medium. The effect is observed from 10‐7M NA and gradually increases so that at 10‐4M NA in the medium the net loss is small. By continuous removal of the NA in the medium by addition of potassium ferricyanide, the net loss reaches a maximum value which may represent the basic release rate. The effect of NA in the medium is due to reuptake of NA as indicated by the incorporation of dI‐3H‐NA in the granules during incubation. Preliminary observations suggest that the reuptake is also ATP‐dependent. During successive depletion of labelled stores at 20d̀, the specific activity of NA is unalterec indicating a uniformly labelled pool. In partially NA depleted nerve granules the net uptake of NA from the medium is enhanced by ATP‐Mg2and dependent on the NA concentration in the medium. A method for estimating the relative affinity of the l‐ and d‐isomer for nerve granules is described. The mean value found for the affinity ratio l‐NA/d‐NA was 9.4 (range 4.2–15.7). It is suggested that the continuous turnover of NA in the nerve storage granules is of major significance for the physiological

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03721.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThe application in the rabbit of a radiospirometric technique using133Xenon and external detectors is described. The ventilation and the perfusion could be measured separately for each lung. In unilateral hypoxia the method revealed a reduced perfusion of the hypoxic lung.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03722.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThe present work deals with the effects of the anions Cl, Br, NO3, I, SCN, and HCO3on Na and K fluxes, and on glucose metabolism of human red cells suspended in isotonic electrolyte media at 38d̀ C and pH 7.40 in the presence of ouabain. When 120 m M Cl of the isotonic medium was substituted by the anion concerned, Na influx and K efflux were unaffected by Br, increased about 30 per cent by NO3and I, but increased 200 to 250 per cent in the presence of SCN. Substitution of 120 mM Cl by HCO3increased Na influx into red cells by 250 per cent. In contradistinction K efflux was reduced by 25 per cent. The increase of Na influx was linearly related to HCO3concentration at pH 7.40.At intracellular Na concentrations between 10 and 35 meq/kg cell water the rate constant of Na efflux was close to 0.15 h‐1in the presence of all 6 anions studied. At external K concentrations from 5 to 7.6 meq/l potassium influx into ouabain treated cells suspended in a chloride medium was thrice as big as the influx calculated from the flux ratio equation M1/M0=K0/K1. exp (‐zEF/RT). A similar condition was found in the presence of Br. In all other media studied (NO3.l, SCN, and HCO3) the ratio between the measured fluxes of potassium agreed with the calculated values of flux ratio for passive, independent fluxes.A net flux of water into the cells was observed in cells suspended in SCN and HCO3media. In the same media the gain of Na in cells exceeded K loss. The relation of water net flux to the net gain of cations was 6.5–7.3 g water per meq. The rate of glycolysis was unaffected by the substitution of Cl by HCO3, was reduced by 15 per cent in the presence of Br, NO3, and I, and decreased by 30 per cent in the presence

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03723.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractA method for measuring glucose concentrations down to 10 μM/L is described. This is a modification of a method based on a commercially available glucose‐oxidase reagent. Some factors which are important for good reproducibility were investigated. Most important is the light sensitivity of the chromogenic reaction. The absorbance decrease which results from illumination is, however, reversible in the dark. If the samples are kept in darkness until the absorbance is measured and a suitable photometer is used, the method has a good reproducibility and is simple to perfo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03724.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The hyperpolarization of the contraluminal acinar cell membrane which takes places when the submandibular gland is stimulated, is called the secretory potential. Much indirect evidence has been presented in favour of the hypothesis that the mechanism of establishment of this potential is due to an active electrogenic chloride transport, and not to a change of the membrane permeability for ions. This transport should be responsible for the formation of the saliva. If this is true, both secretory potentials and secretion should be inhibited to the same degree by metabolic inhibitors. In the present work it was found that the metabolic inhibitors dinitrophenol and cyanide and the cardiac glucoside g‐strophantin (ouabain) had the ability to inhibit completely both secretion and secretory potentials in the perfused cat submandibular glan

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03725.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

It has previously been shown that the cat submandibular gland is unable to secrete in the absence of calcium. As the formation of saliva is the result of transport processes in the acini as well as the duct system, the effect of omitting calcium was investigated in both these parts of the gland. In the acini secretory potentials which are signs of an active ion transport, were recorded, and in the duct system water permeability was measured using tritium labelled water. In spite of severe reduction in the secretory ability of the gland, secretory potentials of normal size could still be evoked in the absence of calcium, but the shape of the potentials was altered. No striking effects on the water permeability of the duct system could be detected.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03726.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Amino acid uptake by isolated whole ovaries from prepuberal rats has been studied employing the non‐utilizable amino acids α‐amino‐isobutyric acid (AIB) and 1‐aminocyclopentane carboxylic acid (cycloleucine), as well as the normal amino acid proline. The ovaries showed a nearly linear uptake of AIB during 4 hrs of incubation while cycloleucine reached steady‐state levels in the tissue after approximately 1 hr. The uptake of proline resembled that of cycloleucine. Ovaries from rats which had received an i.v. injection of FSH before the extirpation of the ovaries showed both a higher rate of AIB‐uptake and higher levels in the steady‐state distribution of cycloleucine than ovaries from control rats. Dose‐response relationships as well as the importance of the time interval between the FSH injection and the start of incubation were analysed. Addition of FSH directly to the incubation medium had no stimulatory effect on amino acid uptake. Intraperitoneal injection of puromycin before the injection of FSH blocked the effect of the hormone on AIB‐uptake. Various possibilities to explain the lack ofin vitroeffect of FSH on amino acid uptake are discussed in relation to the observati

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03727.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractThe effect of a cold and warm environment on the activity of the central catecholamine (CA) and 5‐hydroxytryptamine (5‐HT) neurones has been studied with the help of a combined biochemical and histochemical approach using inhibitors of the tyrosine and tryptophane hydroxylase. The central noradrenaline (NA) and 5‐HT neurones of rats kept at: 40d̀ C were found to increase their state of neuronal activity. whereas the 5‐HT but not the CA neurones of rats kept at ± 3d̀ C showed a decreased neuronal activity. These results indicate that the central NA and 5‐HT neurones participate in therm

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1967.tb03728.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY