Sarcoplasmic Resistivity of Normal and Dystrophic Muscle Fibers of Mice

Abstract

The electrical resistance of normal glass microelectrodes was calibrated against surrounding solutions of different resistivities. At 10−8 A A.C. (1 kHz) the voltage drop across the KCl-calibrated electrode, inserted into muscle fibers, gives some indication of the cytoplasmic resistivity r. The means ± standard error in units of Ω centimeters yielded for normal and dystrophic M. gastrocnemius 138 ± 4 and 125 ± 6, and for normal and dystrophic M. soleus 166 ± 8 and 135 ± 4. The r values of maximal probability are 18–34 Ω cm lower. These r values are higher than rh, the resistivity expected from the ion content in homogeneous distribution. On the basis of Maxwell's equation for the resistivity of suspensions, this result, as well as the dystrophic fibers' lower r value, may be explained if one assumes a higher degree of inhomogeneity of ion distribution in the normal muscle fiber.