摘要:

AbstractIn 121 healthy men aged 30–83 years heart rate, oxygen uptake, arterial lactate and pyruvate concentrations were studied during stepwise increased work loads on a bicycle ergometer. The relationship between heart rate and work load was not affected by age but the final heart rate and work load decreased with age. In the younger ages the most usual reason for breaking off the test was fatigue in the legs, in the higher ages dyspnoea. The regression line for log lactate on heart rate during exercise was on a higher level in old men than in young. Blood lactate during exercise was correlated both to the degree of circulatory steady state, the heart rate, and the final work load irrespective of age. The relationship between lactate and excess lactate during exercise was similar in old and young men, excess lactate being equivalent to lactate reduced by 2 mM/1. In 20 men aged 60–83 years there was at 600 kpm/min a negative correlation between mechanical efficiency and heart rate and a positive between oxygen uptake and weight or heart rate. No correlation was found between oxygen uptake or mechanical efficiency and age, degree of circulatory steady state or blood lactate concentrat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02883.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe spontaneous depletion of endogenous noradrenaline (NA) from bovine splenic nerve granules is diminished or prevented by incubation with either L‐NA or D‐NA. However, the effect observed following the addition of L‐NA is significantly greater than that produced by the D‐isomer. No significant difference is observed between the uptake of the two isomers of adrenaline (A) in undepleted granules. The enhanced uptake of A or NA in a concentration of 10 üg/ml in the presence of adenosine triphosphate (ATP) similarly did not differ for the L‐ and D‐isomers of the amine. However, the ATP‐ dependent uptake at an amine concentration of 1 μg/ml was 2–3 times as high for L‐NA and L‐A than for the D‐isomers.It is concluded that the ATP‐dependent uptake in nerve granules of NA and A at low amine concentrations is to some extent stereospecific, while the amine‐uptake at higher concentrations with and without added ATP is not or only slightly dependent

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02884.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractObservations were made of the mechanical and electrical activity of intrafusal muscle fibres in semi‐isolated muscle spindles fromXenopus laevis.The spindle capsule, which formed a part of the recording system, was studied and was found to be a a laminated, ohmic, structure with a characteristic length of approximately 0.7 mm. Electrical and histological evidence combined with observations of the movements of the intrafusal muscles led to the conclusion that the intrafusal muscle bundle consisted of either two or three muscle fibres and that these muscle fibres could be divided into large and small diameter groups. The large diameter muscle fibres showed a fast contraction in response to single stimuli, and were supplied by large diameter motor nerves. The small diameter muscle fibres showed a very slow contraction in response to single stimuli and were supplied by small diameter motor nerves. Evidence was obtained that the innervation of the large and the small fibres did not overlap. The electrical event in both types of muscle fibre was conducted transcapsularly except on repetitive stimulation, and external current records indicated that the membrane potential change in the small muscle fibres was considerably longer than in the large fibres. Transcapsular conduction failed in the large fibres at a a stimulation rate of approximately 30/sec, and in the small fibres at 5/sec. This conduction failure was associated with a fusion of contraction on the innervated side of the preparation. Evidence was obtained that a region of low safety factor exists in the large intrafusal muscle fibres in the approximate region of the sensory contact

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02885.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe spatial distribution, amplitude distribution and interval distribution of spontaneous Junctional potentials of fast and slow muscle fibres of the myotomal parietal muscle of the hagfish have been studied. The fast muscle fibres are focally innervated with an end‐plate area localized to one end of the fibre whereas the synaptic regions of the slow muscle fibres are distributed along their entire length. The mean distance between the synaptic sites of the slow muscle fibres is less than 0.1 mm. The electrical cable constants of the two types of fibre have been determined by passing square waves of current through the membrane and recording the changes in membrane potential. The specific resistance of the membrane of the slow fibres is unusually hig

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02886.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractIron metabolism in tench was studied. At 18° up to 70 per cent of injected Fe59was taken up by the erythrocytes. In the first days of the experiment an appreciable part, up to 20 per cent, of the Fe59is present in the erythrocytes as non‐hemoglobin iron, the latter decreases with time. Hemoglobin (Hb) concentration amounted to 5.4 g%, erythrocyte number 1.04×106per mm3. Serum iron was found to be 61 ü g% and iron binding capacity 250 üg%. Plasma iron half disappearance rateis4 hours. In fish kept at 5° iron taken up by erythrocytes amounts to 4 per cent only. Both in at 18° and 5° kept fish one Hb fraction and one transferrin fraction was found only. At high oxygen concentration or in nitrogen atmosphere less Fe59is incorporated in in vitro experiments into erythrocyte hemin than in air. The life time of about 60 per cent of erythrocytes amounts to about 150 days at 18°, indications of longer‐living erythrocytes

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02887.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractCoagulation studies were performed in 15 dogs subjected to cooling to 20° C under various conditions. Thrombocytopenia invariably occurred during the cooling process. Hypothermia alone was followed by decrease of fibrinogen and prothrombin and factor VII and by an increased fibrinolytic activity and antithrombin activity. Hyperactive factor V levels were recorded during hypothermia and the plasma also showed thromboplastic activity. Administration of e‐ACA to the dogs before and during the hypothermia prevented the development of fibrinolytic activity but it did not prevent the decrease of fibrinogen and prothrombin and factor VII. Hyperactive factor V levels were recorded during the cooling as well as a marked thromboplastic activity in the plasma. Administration of heparin to the dogs before and during the hypothermia prevented the decrease of fibrinogen. The fibrinolytic activity was not prevented. No hyperactive factor V levels occurred. Simultaneous administration of heparin and e‐ACA to the hypothermic dogs prevented both the decrease of fibrinogen and the fibrinolytic activity.It is concluded that the coagulation defects induced by hypothermia are due mainly to intravascular coagulation. The decrease of fibrinogen which takes place in connection with hypothermia is due to its consumption in the coagulation process and not caused by the fibrinolytic process. It appears unwise to use ε‐ACA alone during hypo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02888.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe study was undertaken to evaluate the rôle of the lymphatic drainage of the calf muscles of cats in the transport of fluid and proteins from exercising muscle. Pure muscle lymph was obtained from a deep lymph vessel above the knee after exclusion of the paw which otherwise contributes substantially to the flow of lymph in the deep vessels. During exercise the lymph flow in skeletal muscles increases but even then accounts for only some 10 per cent of the simultaneously produced capillary filtrate. The protein content of lymph from muscle was about the same as that of lymph from skin. The albumin fraction in muscle lymph was moderately raised compared with that of plasma and did not change during exercise. The lymph can probably drain the entire protein content of the capillary filtrate produced during exercise

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02889.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractLymph flow from, and volume changes in, muscles during exercise were recorded simultaneously. During exercise there occurs an outward filtration at an initially steady rate. This filtration gradually diminishes and finally ceases. Under the experimental conditions used lymph flow was very small compared with the rate of outward filtration. The capillary filtrate accumulated in the muscle. The amount of fluid accumulated varied with the work load. The factors limiting outward filtration are discussed. The most important limiting factors seem to be gradually rising tissue pressure, and to some extent changes in colloid osmotic pressure on either side of the capillary wall.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02890.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02891.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1964.tb02892.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY