Effects of electrical constants on conduction velocity of action potentials measured with unidimensional latency-topography in frog skeletal muscle fibers.

Conduction velocity (CV) of an action potential recorded from a single muscle fiber of the frog was measured with a new method, unidimensional latency-topography, and electrical membrane constants were determined for the same muscle fiber. CV = 1.96 +/- 0.27 m/sec (n = 52) at about 20 degrees C. Temperature coefficient of CV: Q10 = 2.0. Electrical membrane constants in the same muscle fibers (n = 52): lambda = 3.25 +/- 0.83 mm, tau = 33.4 +/- 14.3 msec, Cm = 6.09 +/- 2.13 mu F/cm2, D = 129.4 +/- 28.9 micron (mean +/- S.D.). The CV decreased linearly with increment of time constant, tau, and membrane capacity per unit area, Cm. The space constant, lambda, and the fiber diameter of the muscle fiber, D, did not correlate with CV. It was concluded that the T-system, which contributes largely to membrane capacity, has a great influence on the CV.