scholarly journals The effect of membrane polarization on the time course of the end-plate current in frog sartorius muscle

1969 ◽  
Vol 204 (2) ◽  
pp. 493-502 ◽  
Author(s):  
M. Kordaš
2018 ◽  
Vol 14 (8) ◽  
pp. 1198-1202 ◽  
Author(s):  
Ayrat Usmanovich ◽  
Rafis Rustemovic ◽  
Azat Iskhakovic ◽  
Adel Evgenyevic ◽  
Sergey Nikolaevic

1959 ◽  
Vol 196 (6) ◽  
pp. 1191-1196 ◽  
Author(s):  
S. Ochs ◽  
A. K. Mukherjee

Resting potentials of frog sartorius muscle fibers were taken with microelectrodes at different distances along the length of muscles before and after adding acetylcholine or choline. The mean membrane potential drop and scatter of the potentials recorded in the relatively nerve-free, and in the more densely innervated parts of the muscle, were similar. The loss of direct excitability to electrical and mechanical stimulation was correlated with the concentration of choline or acetylcholine presented. d-tubocurarine added beforehand protected against the depolarizing effect of acetylcholine and choline everywhere along the length of the muscle. A generalized action of acetylcholine and choline and also of d-tubocurarine all along the muscle fibers was inferred. This generalized action at higher concentrations of acetylcholine and choline is believed to be additional to a more specific end plate action.


1978 ◽  
Vol 71 (5) ◽  
pp. 559-580 ◽  
Author(s):  
M Mahler

The time-course of the rate of oxygen consumption (QO2) has been measured in the excised frog sartorius muscle after single isometric tetani of 0.1-1.0 s at 20 degrees C. To measure deltaQO2(t), the change in QO2 from its basal level, a novel method was devised, based on the validity in this tissue of the one-dimensional diffusion equation for oxygen, established in the preceding paper. After a tetanus, deltaQO2 reached a peak within 45-90 s, then declined exponentially, and could be well fit by deltaQO2(t) = QO + Q1(epsilon -k1t - epsilon-k2t). tau2 (= 1/k2), which characterized the rise of deltaQO2, was a decreasing function of tetanus duration (range: from 1.1 +/- 0.28 min [nu = 5] for a 0.1-s tetanus, to 0.34 +/- 0.05 min [nu = 8] for a 1.0-sec tetanus). tau1 (= 1/k1), which characterized the decline of deltaQO2, was not dependent on tetanus duration, with mean 3.68 +/- -.24 min (nu = 46). A forthcoming paper in this series shows that these kinetics of deltaQO2 are the responses to impulse-like changes in the rate of ATP hydrolysis. The variation of tau2 with tetanus duration thus indicates the involvement of a nonlinear process in the coupling of O2 consumption to ATP hydrolysis. However, the monoexponential decline of deltaQO2(t), with time constant independent of tetanus duration, suggests that during this phase, the coupling is rate-limited by a single reaction with apparent first order kinetics.


1978 ◽  
Vol 71 (5) ◽  
pp. 533-557 ◽  
Author(s):  
M Mahler

Adaptations of the method of Takahashi et al. (1966. J. Gen. Physiol. 50:317-333) were used to test the validity of the one-dimensional diffusion equation for O2 in the resting excised frog sartorius muscle. This equation is: (formula: see text) where x is the distance perpendicular to the muscle surface. t is time, P(x, t) is the partial pressure of O2,D and alpha are the diffusion coefficient and solubility for O2 in the tissue, and Q is the rate of O2 consumption. P(O, t), the time-course of PO2 at one muscle surface, was measured by a micro-oxygen electrode. Transients in the PO2 profile of the muscle were induced by two methods: (a) after an equilibration period, one surface was sealed off by a disc in which the O2 electrode was embedded; (b) when PO2 at this surface reached a steady state, a step change was made in the PO2 at the other surface. With either method, the agreement between the measured P(O, t) and that predicted by the diffusion equation was excellent, making possible the calculation of D and Q. These two methods yielded statistically indistinguishable results, with the following pooled means (+/- SEM): (formula: see text) At each temperature, D was independent of muscle thickness (range, 0.67-1.34 mm). The activation energy (EA) for diffusion of oxygen in muscle was -3.85 kcal/mol, which closely matches the corresponding value in water. Together with absolute values of D in water taken from the literature, the present data imply that (Dmuscle/DH2O) is in the range 0.59-0.69. This value, and that of EA, are in agreement with the theory of Wang (1954, J. Am. Chem. Soc. 76:4755-4763), suggesting that with respects to the diffusion of O2, to a useful approximation, frog skeletal muscle may be considered simply as a homogeneous protein solution.


1982 ◽  
Vol 29 (4) ◽  
pp. 183-187 ◽  
Author(s):  
YHUKOU OHTA ◽  
TAKASHI AKASU ◽  
KYOZO KOKETSU

Nature ◽  
1965 ◽  
Vol 206 (4991) ◽  
pp. 1358-1358 ◽  
Author(s):  
H. E. HUXLEY ◽  
W. BROWN ◽  
K. C. HOLMES

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