摘要:

The influence of duration of vascular occlusion upon the reactive hyperemic response in human cutaneous tissue was studied in 6 subjects. Blood flow in cutaneous tissue was measured dorsally on the distal phalanx of the second finger by the local133Xenon washout technique. Post‐occlusive blood flow, calculated from the steepest part of the133Xenon washout curve just after release of vascular occlusion, reached a maximum value when duration of vascular occlusion was 12 min. However, excess cumulative blood flow, i.e. the integrated blood flow during reactive hyperemia minus integrated pre‐ischemic blood flow for a period corresponding to the duration of the reactive hyperemic response, increased with increasing duration of vascular occlusion from 3 to 24 min. Fractional repayment, i.e. excess cumulative blood flow divided by pre‐ischemic blood flow times duration of vascular occlusion, was not correlated significantly to duration of vascular occlusion. However, there was a significant inverse correlation between fractional repayment and pre‐occlusive blood flow, indicating that, besides metabolic factors, pre‐ischemic blood flow in cutaneous tissue is influenced by other factors, such as heat r

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06493.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A comparative analysis of the effects of externally applied Rb+, Cs+, Sr2+, Ba2+and La3+on myelinated fibres under potential clamp conditions was made. The ions Cs+, Ba2+and La:l+(belonging to groups 1a, 2a and 3a of period 6 in the periodic system) were found to affect the K system in specific ways. Ba2+and La3+reduced the outward K+current associated with positive potential steps; the effect of La3+being larger than that of Ba2+. The effect of Ba2+depended on the K+concentration. Cs+, Ba2+and La3+reduced the inward K+tail current at repolarisation in solutions with high K+concentration. Cs+and Ba2+caused a rectification of the K+current, i.e. they reduced the inward tail current proportionally more than the outward steady state current. The effect of Baz+could not be described as a simple reduction of the permeability constant p¯K. Rb+was found to affect the time course of the K system by increasing the rate constant βn. Sr2*, Ba2+and La3+reduced the permeability constant p¯Na. These ions also shifted potential dependent parameters in general along the potential axis. The effect of La3+was larger than that of Sr2+and Ba2+. Cs2+, Ba2+and La3+reduced the p‐current, Ba2+and La3+the leak conduct

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06494.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The effects of physical training on the metabolism of collagen, calcium and glycosaminoglycans in various connective tissues were studied in male NMRI mice. The mice to be trained and their controls were about 3 weeks old (expt. I) and 8 weeks old (expt. II) at the commencement of training. The training was performed on a 5° inclined treadmill 5 days a week for 4 weeks in expt. I and for 3 weeks in expt. II. The daily exercise time was progressively increased from 20 min in the first week up to 80 min in the third week. The incorporation of3H‐proline to collagen hydroxyproline was increased by training in long bones, skeletal muscle and Achilles tendon, whereas the incorporation of35S‐sulphate into glycosaminoglycans of bones was lower for the trained compared to the control mice. The differences between the two groups in the incorporation of45calcium were negligible. The results indicate that the metabolism of collagen is accelerated by physical training in several connective tissues in young rapidly growing mice, whereas the metabolism of glycosaminoglycans remains uneffected or is even reta

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06495.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The effect of external Ca, Mg, Sr, Ba and La concentration was studied in potential clamp experiments on single myelinated nerve fibres of the frog (Xenopus laevis). An increase in cationic concentration caused a positive shift of the Na permeability (PNa) curve along the potential axis, a decrease in max.PNaand a decrease in the slope of thePNacurve. The effectiveness of Mg, Sr and Ba was similar and about 0.6 compared to that of Ca, whereas La was about 80 times more effective than Ca.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06496.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

This work deals with the possibility that cations may be transported through the human red blood cell membrane as negatively charged ion pairs of the type XCO3‐. Passive sodium influx into human erythrocytes was increased 4‐fold when 150 mM chloride was substituted with bicarbonate in the medium. This increased permeability to sodium was completely abolished when the cells were pretreated with a specific inhibitor of anion transport (DIDS). Both bicarbonate‐induced sodmm influx and chloride exchange were linearly related to DIDS‐binding. Both transport processes were completely inhibited by the binding of 1.1X 106DIDS molecules per cell. The presence of bicarbonate and/or pre‐treatment of the cells with DIDS did not change the permeability of the erythrocyte membrane to K+, Rb+, and Cs+to any significant extent. The experimental findings support the hypothesis that Li+and Na+, but not K+, Rb+, and Cs+form monovalent negatively charged ion pairs with CO3‐, which traverse the membrane through the anion exch

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06497.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Pre‐and postjunctional control mechanisms of the portal vein of spontaneously hypertensive rats (SHR) were characterized. Emphasis was placed on the influence of the presynaptic beta‐adrenoceptor mediated mechanism for regulation of neuronal noradrenaline (NA) release (studied as tritium overflow) and its consequences for the contractile response under in vitro conditions. It was found that isoprenaline increased, whereasdl/‐propranolol decreased the release of neuronal NA during transmural nerve stimulation, while effector responses remained unaltered.d‐Propranolol and the beta‐1 selective adrenoceptor antagonist, metoprolol, did not affect these two variables. It is concluded that the presynaptic beta‐adrenoceptors in the rat portal vein are mainly of the beta‐2 type and mediate facilitation of neuronal transmitter release and that concomitant changes of the effector responses of this tissue are below the level of detection under the present experiment

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06498.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A stochastic nerve membrane model with a two‐state pore system was investigated by computer simulation in the uniform (space‐clamped) case. The model was based upon the Hodgkin‐Huxley equations for the giant axon in squid, but where both the maximal membrane conductances and the rate constants were changed systematically. This was done in order to simulate nerve membranes of small axons, where both of these parameters are smaller than in squid. It was found that the effects upon the firing behaviour due to a finite number of pores were not greatly affected by changes in these parameters. When the specific injected current was calculated relative to the maximal membrane conductances, the threshold for firing was increased somewhat, and the frequency‐current relationship became slightly more linear when the maximal conductances (or pore density) were decreased, or the rate constants increased. In the discussion it is shown how the results obtained could be applied qualitatively to the firing behaviour of nerve cells, and that firing in small nerve cells should be significantly influenced by the stochastic effects of a finite number of pores. Gating currents were also discussed, and their effects were found to be insignificant in small nerv

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06499.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Transversal sections of the inferior oblique muscle from kittens of various ages and from adult cats were stained for myofibrillar ATP‐ase at Ph 9.4 and 4.35, succinic dehydrogenase (SDH) and fat. The same muscles had previously been submitted to studies of contractional and fatigue properties. With ATPase the fibers could be differentiated into types I, II and II C. The percentages of each fiber type remained approximately the same from birth onwards. In the inner, global layer of the muscle, type I fibers showed a linear increase in size, but types II and IIC fibers an accelerated growth after age 20 weeks. In the outer, orbital layer, where no type I fibers were seen, types II and IIC fibers showed the same growth pattern as in the global layer. The fiber content of SHD and fat was low at birth but increased after two weeks of age. Type I fibers were poor and type IIC fibers rich in SDH and fat. Type II fibers showed varying amounts of these substances. Provided that type 1 fibers are slow, type II fast and type II C intermediate in speed of contraction, like in other muscles, the findings on fiber growth and SDH content seem to support the idea that slow, fatigue resistant components in eye muscles reach maturity earlier than fast component

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06500.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The “tail‐cuff technique for indirect blood pressure measurements was standardized, with respect to heating, in experiments on 47 adult Sprague‐Dawley rats. The direct, intra‐arterial, and the indirect blood pressures were simultaneously obtained. Pulse volume was recorded from the tail by a non‐invasive technique, and was controlled by gradual application of heat. It was found that pulse volume and body temperature were poorly related. A stable relation existed, however, between the error in the indirect blood pressure recordings and the pulse volume. The error was minimized, provided that the heating was adjusted to induce a pulse volume of at least 25% of the maximum obtainable value. It was suggested that the validity of the indirect blood pressure recording could be improved, if heat application was regulated on the basis of observations of pulse volume in the tail instead of ambient temperature or body temperature. Errors due to excessive vasoconstriction, or discomfort due to overheating could thereby be

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06501.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A marked β‐adrenergic dilator interaction with the vasoconstrictor response in skeletal muscle during hemorrhage is described. The dilator influence corresponded to some 40% of the constrictor response both at mild and moderate as well as at large bleeding. In absolute resistance units, the β‐adrenergic dilator influence averaged no less than 14 mmHg/(mlXmin‐1X 100 g‐1) at large bleeding (hemorrhagic hypotension of 50 mmHg). Comparison of the hemorrhage induced resistance effects in the autoperfused innervated muscle, in the autoperfused denervated muscle, and in the innervated muscle cross‐circulated from a donor animal, showed that the β‐adrenergic dilator influence more or less completely was caused by blood‐borne catecholamines, in all likelihood by adrenaline, which is known to be secreted in large amounts during hemorrhage. The described β‐adrenergic dilator mechanism may serve to maintain nutritional blood flow by counteracting the constrictor response. It deserves consideration also from the point of view that it obviously has to be taken into account for proper evaluation of other vascular control mechanisms brought into a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1980.tb06502.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY