摘要:

AbstractCardiac output, stroke volume, right heart and left heart blood volume, pulmonary blood volume and pulmonary mean time were measured at rest and during muscular exercise in 14 healthy subjects in the supine position. The method used was113mIn radiocardiography measured precordially with a single detector. The results were analyzed with a minicomputer by a modified gamma function fitting method. The increase in cardiac output during exercise was 140 per cent (p<0.001). The stroke volume increased 15 per cent (p<0.05) in subjects with heart rates0.1) and the left heart blood volume decreased from 115 ml/m2to 105 ml/m2(5 per cent; p<0.01). The total heart blood volume thus decreased from 120 ml/m2to 110 ml/m2(5 per cent; p<0.01). The pulmonary blood volume showed a corresponding increase from 250 ml/m2to 280 ml/m2(12 per cent; p<0.005), and the cardiopulmonary blood volume did not markedly change (485 ml/m2and 495 ml/m2). Pulmonary mean time decreased from 5.0 s to 2.4 s (52 per cent; p<0.001

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10037.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractMuscle biopsy samples were obtained from healthy subjects in order to evaluate quantitative differences in single fibres of substrate (glycogen and triglyceride) and ion concentrations (Na+and K+) as well as enzyme activity levels (succinate‐dehydrogenase, SDH; phosphofructokinase, PFK; 3‐hydroxyacyl‐CoA‐dehydrogenase, HAD; myosin ATPase) between human skeletal muscle fibre types. After freeze drying of the muscle specimen fragments of single fibres were dissected out and stained for myofibrillar‐ATPase with preincubations at pH's of 10.3, 4.6, and 4.35. Type I (“red”) and II A, B, and C (“white”) fibres could then be identified. Glycogen content was the same in different fibres, whereas triglyceride content was highest in Type I fibres (2–3 × Type II). No significant differences were observed for Na+and K+between fibre types. The activity for the enzymes studied were quite different in the fibre types (SDH and HAD, Type I ≊ 1.5 × Type II; PFK Type I ≊ 0.5 × Type II; Myosin ATPase Type I ≊ 0.4 × Type II). The subgroups of Type II fibres were distinguished by differences in both SDH and PFK activities (SDH, Type II C>A>B; PFK, Type II B>A ≊ C). It is concluded that contractile and metabolic characteristics of human skeletal fibres are very similar to many other species. One difference, however, appears to be that no Type II fibres have an oxidative pote

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10038.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe isometric responses of the medial gastrocnemius (MG), soleus (SOL) and anterior tibial (TA) muscles to single shocks and different modes of repetitive stimulation were studied in kittens of varying postnatal ages and in adult cats. The postnatal decrease in time‐to‐peak and half‐relaxation time of the twitch contractions was similar for the MG and TA muscles and adult values were attained at around 6–7 weeks of age. The SOL muscle displayed a transient decrease in contraction time during the first postnatal weeks, followed later by a slowing towards adult values. The susceptibility to fatigue during iterative stimulation was smallest in the SOL at all ages studied, and usually largest in TA. It changed only little for the MG and SOL postnatally while increasing markedly for the TA up until 6–7 weeks of age. Tetanic contraction resulted in similar depressions in contractile tension of all three muscles in the youngest kittens, but the SOL displayed a greater ability to recover from this depression than the MG and, in particular, the TA muscles. Tetanus resistance increased postnatally and adult responses were attained at 6–7 w

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10039.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe importance of passive‐elastic changes of vascular dimensions and shifts in regional effective viscosity for the pre‐/postcapillary resistance ratio (RA/RV), and hence mean capillary pressure (PC), was analyzed in cat calf muscles. Reductions of mean venous distending pressure below 6–8 mm Hg induced marked R, increases due to escalating venous collapse. This mechanism tends to delimit the PCreductions and rate of transcapillary fluid absorption during intense precapillary vasoconstriction. Comparisons of RA/RVfor erythrocyte suspensions (Hct 40–50) and cellfree perfusates at identical vascular dimensions showed that RA/RVwas considerably higher, and P, correspondingly lower, for the erythrocyte suspension except at very low flows. This RA/RVdifference increased with increasing flow and at very high flows P, was about 10 mm Hg lower during perfusion with the erythrocyte suspension. These findings apparently diverge from the known influence of tube radius and linear flow velocity on effectivein vitroviscosity of blood. Since distal precapillary and proximal capillary sections, both having smaller diameters than the erythrocytes, are located upstream to the point of filtration‐absorption equilibrium, they contribute in this respect to RA. It is therefore suggested that the increasing RA/RVwith erythrocyte perfusion, particularly at higher flows, is not due to genuine viscosity factors but to friction losses when cells in “bolus flow” are squeezed through the narrowest precapil

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10040.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe glomerular filtration process was evaluated theoretically from micropuncture data obtained from Sprague‐Dawley rats. The hydrostatic pressures in the glomerular capillaries and Bowman's space minus the oncotic pressure in systemic plasma gave the net driving force at the proximal end of the glomerular capillary. From the single nephron filtration fraction the mean net driving force over the glomerular membrane was calculated to be 20 mm Hg during normotension, decreasing to 12 mm Hg during a perfusion pressure of 80 mm Hg. The hydraulic permeability for one glomerulus was 0.7‐0.8 nl/min. 100g b. wt. mmHg. The pressures at the distal end of the glomerular capillaries were 13 and 6 mm Hg under the above two conditions, indicating non‐equilibrium of the filtration process at the end of the glomerular capillary. It was shown that the glomerular filtration rate is mainly influenced by the driving pressures. During hypotension an increased plasma flow dependency was evident. Brenneret al.found a filtration equilibrium and a plasma flow dependent glomerular filtration rate in a mutant Wistar rat strain. The discrepancy between their results and ours is due to the low glomerular plasma flow and hydrostatic pressures in the Wistar rats. It is concluded from our results that both pre‐ and postglomerular resistances may influence the glomerular filtration rate and glomerular plasma flow indepe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10041.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10042.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10043.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb10044.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY