摘要:

AbstractTwitches were recordedin situin muscles of normal humans by small transducers connected to a needle in the tendon. The twitches were elicited by stimuli in the endplate zone, the force of the smallest twitches corresponding to the average of one or two motor units. The time to peak contraction was measured of 20–30 bundles of fibres in each muscle examined. The histograms of contraction times agreed with histochemical findings; contraction times longer than 60 msec corresponded to the proportion of fibres rich in mitochondria. Thus, long contraction times predominated in the soleus and gastrocnemius muscles, comprised half the times in the anterior tibia], a third in the brachial biceps (long head) and a few per cent in the brachial triceps muscle (lateral head). Bundles of fibres with short contraction times, those poor in mitochondria had a higher temperature coefficient of the time to peak than bundles with long contraction times. During hypoxia the contraction times shortened. The contraction time of motor units first activated voluntarily lay near the mean of bundles activated electrically. The contraction times of fasciculating fibres were in the range of electrically evoked twitches; the force was about three times that of voluntarily activated unit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04744.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIt has been assumed that the main resistance to sodium ion movements is located in the superficial layer of the amphibian skin. It is therefore of interest to follow transport function during shedding of thestratum corncum. Shedding of thestratum corneumin the isolated toad skin (Bufo bufo) can be induced by aldosterone treatment of skin from hypophysectornized toads. It is shown that slough formation is followed by an almost three fold increase in short‐circuit current. This increase is accounted for by an increased rate of active sodium transport and is preceded by an increase in passive sodium permeability and a decrease in D.C. resistance. The results are discussed in relation to the functional organization of the skin, and to moultingin viv

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04745.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe structure of myoneural junctions induced during nerve regeneration outside the zone of previously existing, degenerating myoneural junctions was studied with the light microscope after histochemical demonstration of acetylcholinesterase (AChE) activity in the tibialis anterior muscle of the postnatal rat. The escape of regenerating nerves from their original glial sheaths was produced by severe crushing of the sciatic nerve at different stages of development of the rat, from newborn animals to adults. New myoneural junctions were induced in the previously undifferentiated part of the muscle plasma membrane in animals of all age groups, although not in every individual animal, if the old myoneural junctions did not regenerate. New myoneural junctions were observed in about 70 % of the rats operated on before the age of 10 days and in less than 20%in the older groups. The older the animal, the fewer new myoneural junctions were seen among the re‐innervated old ones, and in the adult animals a new myoneural junction was only sporadically foundMyoneural junctions were first seen outside the zone of previously existing junctions 14–16 days after the operation. Irrespective of the age of the animal at operation, the postnatally induced myoneural junction was plate‐like in structure during the early stages of morphogenesis. Postsynaptic infoldings appeared between the 16th and 25th days after the operation, the infoldings had become deeper between the 25th and 35th days, and the ramification of the AChE distribution typical of the mature myoneural junctions was observed between the 35th and 45th postoperative

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04746.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect on arterial blood pressure of pretreatment with Trasylol was studied in dogs injected i.v. with homologous brain thromboplastin. Trasylol did not consistently inhibit the initial fall in arterial blood pressure, but the return to normal pressure level was faster after administration of the drug. This effect of Trasylol might depend on interference with coagulation processes as well as with release of vasoactive substances.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04747.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effects of mild exercise dehydration (1 % of the body weight) on temperature regulation were investigated in 3 men during continuous and intermittent exercise of 1 hr duration on a Krogh bicycle ergometer with the same average heat production at a relative O2uptake of 62 % in the environment‐independent zone (22° C Taand 38%rh). In both hydration and dehydration, during intermittent work, equilibrium levels of rectal temperature (Tre) were 0.3° C higher than during continuous work. Progressive dehydration elevated equilibrium levels of Tre and mean body temperatures 0.3 to 0.4° C above hydration control values while mean skin temperatures (Ts) were essentially constant at 30±0.2° C. The elevation of Tre with dehydration was due, predominantly, to reduced sweating. It is suggested the sweat depression was due to reduced stimuli from the central nervous system to the glands. These results emphasize the sensitivity of the thermoregulatory system to dehydration and point up the need to control water intake during such exper

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04748.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe mechanism of 5‐hydroxytryptamine (5‐HT) uptake by rat peritoneal mast cells in vitro was studied under different incubation conditions. The uptake reached a saturation level even at low concentration of exogenous 5‐HT resulting in a concentration ratio of more than one thousand times. The uptake during the first hour was more rapid when compared with the slow uptake during succeeding hours. The uptake was dependent on temperature and calcium and magnesium ions. Addition of glucose to the medium did not accelerate the uptake which also was unaffected by pH alteration from 6.0 to 7.4. The proposed active uptake mechanism Tor 5‐HT was supported by the results obtained with metabolic inhibitors; those belonging to the group of uncouplers of oxidative phosphorylation effectively inhibited the uptake while sodium cyanide and sodium azide were without significant effect. Results obtained further indicated that 5‐HT at high exogenous concentrations may passively diffuse into the m

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04749.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of the thrombin‐like enzyme preparation Reptilase, purified from the venom of the snake Bothrops atrox, was studied in dogs injected with125I‐labelled fibrinogen. Reptilase was capable of inducing intravascular coagulation as shown by the decrease in fibrinogen concentration, but influenced the platelet count only moderately. No bleeding tendency was observed. Pretreatment with heparin did not affect the defibrination process. Secondary activation of the fibrinolytic system was demonstrated by the appearance in plasma and serum of fibrinogen degradation products, studied by radioactivity measurements and immunological methods. Epsilon anunocaproic acid (EACA) and Trasylol could reduce and delay but not completely abolish the secondary fibrinolysis. No thromboemboli were found at autopsy.In long‐term treatment by daily injections of Reptilase it was possible to keep the fibrinogen concentration at low levels for several weeks without adverse effects. The hemostatic function was maintained undisturbed probably due to the fact that the platelet count was essentially unch

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04750.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractTissue spaces occupied by14C‐sucrose and3H‐inulin were measured at different incubation time intervals (15–120 min) in rat brain slices prepared from cortex, cerebellum, caudate, diencephalon and midbrain. Total water content, total Na+and K contents and14C‐DMO (5,5‐dimethyl‐2,4‐oxaolidinedione) spaces were obtained from the same tissues. At all time intervals,14C‐sucrose spaces were larger than corresponding3H‐inulin spaces. After 60 min incubation, the mean values for14C‐sucrose spaces in preparations from different brain areas ranged from 31.5 to 38.1 m1/100 g, whereas the3H‐inulin space mean values were 19.3–26.1 m1/100 g. Average intracellular pH was calculated from14C‐DMO spares in the presence and absence of 3.67 mM procaine. The pH1values obtained using inulin‐derived extracellular spares were 6.91–6.99, and those calculated from sucrose spaces were 6.77–6.89. The contents of K+and Na+showed no distinct regional differences, but a potassium uptake with time could only be observed in preparations from

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04751.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThoracic duct cannulated rats were fed 50 μmoles of radioactive cholesterol dissolved in medium chain triglyceride (MCT), hydrogenated coconut oil (HCOCO) or triolein. Lymph was sampled and fractionated with ultracentrifugation and gel chromatography. The amount of lymph lipoproteins was estimated by their lipid content. Gel chromatography showed that there was a continuous distribution of lymph lipoproteins according to molecular size. The transport of chylomicron lipoproteinsi.e. those of Sf>400 increased with fatty arid chain length of the triglyceride used. When MCT or HCOCO were administered the transport of lipoproteins 400>Sf>20 increased. Administration of triolein gave the same transport as HCOCO. While the transport of both lipoprotein classes was lowest when MCT was used. this triglyceride induced the highest transport of cholesterol in lipoproteins 400>Sf>20. This was reflected in the percentage composition of the lipoprotein lipid. It contained more cholesterol and less triglyceride as compared to the other dietary conditions. Exogenous cholesterol was transported in both lipoprotein fractions

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04752.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe ventriculo‐aqueductal perfusion technique was used in order to study the mechanism for transport of glucose, sodium, chloride and potassium between the cerebral ventricles and surrounding tissues in cats. The inflow perfusion fluid contained U14C‐D‐glucose and un‐labelled D‐glucose. With D‐mannose or D‐xylose in the inflow, the unidirectional flux of glucose from the cerebral ventricles was inhibited competitively. Ouabain in the inflow (10‐7M or 10–45M) and potassium‐free inflow reduced the rate of cerebrospinal fluid formation while the tissues lost potassium and gained sodium and chloride. The presence of ouabain reduced the unidirectional flux of glucose from the cerebral ventricles. The effects increased using higher concentrations of ouabain (up to 5 times 10‐5M). Injections of increasing amounts of ouabain into the internal carotid artery had 110 effects upon the above mentioned variables. The results support the idea that ouabain‐sensitive carrier‐mediated transport of glucose from the cerebral ventricles may be connected with the mechanism for

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04753.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY