OBSERVATION OF THE ASYMMETRICAL PHENOMENA IN MEMBRANE OF FROG SARTORIUS MUSCLE FIBERS

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.

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The interactive effects of fatigue and pH on the ionic conductance of frog sartorius muscle fibers

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y85-237 ◽

1985 ◽

Vol 63 (11) ◽

pp. 1444-1453 ◽

Cited By ~ 5

Author(s):

J. M. Renaud ◽

G. W. Mainwood

Keyword(s):

Action Potential ◽

Normal Values ◽

Muscle Fibers ◽

Membrane Conductance ◽

Interactive Effects ◽

Resting Potential ◽

Sartorius Muscle ◽

Ionic Conductance ◽

Frog Sartorius Muscle ◽

Frog Sartorius

The effects of fatigue on the membrane conductance of frog sartorius muscle at the resting potential and during an action potential were studied. When muscles were exposed to an extracellular pH of 8.0 the membrane conductance at the resting potential increased during fatigue by about 20% and returned to prefatigue level in about 20 min. The membrane conductance of muscle fibers exposed to pH 6.4 was about three times less than that of pH 8.0 and decreased further during fatigue. Furthermore, the recovery of a normal membrane conductance was slow at pH 6.4. Both the inward, depolarizing and the outward, repolarizing currents during the action potential are reduced in fatigue. In each case the effect is greater at pH 6.4 than at 8.0 and recovery towards normal values is slower at pH 6.4. It is concluded that the ionic conductance of the sareolemmal membrane at the resting potential and during an action potential are modified by fatigue and that these changes are modulated by pHo.

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Effect of dinitrophenol on phosphorylation and bioelectric phenomena of excitable tissues

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1961.200.3.431 ◽

1961 ◽

Vol 200 (3) ◽

pp. 431-436 ◽

Cited By ~ 18

Author(s):

L. G. Abood ◽

K. Koketsu ◽

K. Noda

Keyword(s):

Energy Metabolism ◽

Muscle Fibers ◽

Resting Potential ◽

Sartorius Muscle ◽

Nerve Roots ◽

Intracellular Potassium ◽

Frog Sartorius Muscle ◽

Anodal Polarization ◽

Frog Sartorius

The effect of 2, 4-dinitrophenol (DNP) was investigated on the phosphorylation of frog sartorius muscle and ventral nerve roots, using P32 as a tracer. It was possible almost completely to inhibit phosphorylation without significantly altering excitability, although the resting potential and intracellular potassium decreased over 30%. The addition of 0.01 mm DNP to a sodium-free hydrazinium system completely blocked excitability, despite the fact that this concentration of DNP produced no further inhibition of phosphorylation. It was possible to restore the excitability of frog sartorius muscle fibers by anodal polarization after the fibers were rendered inexcitable by immersion in 1 mm DNP. The results were discussed in terms of the role of energy metabolism in excitability and other bioelectric phenomena of muscle and nerve.

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