Transmembrane resistance of smooth muscle cells

¹ Department of Physiology, University of Illinois, Urbana, Illinois

Microelectrodes were used to obtain evidence that the cell membrane of vertebrate intestinal smooth muscle cells has a resistance comparable to those obtained for other muscle types. The membrane is thus a barrier of low permeability across which diffusion potentials occur. Resistance measurements between cell interiors and the bathing solution averaged 103.8 megohms and a specific membrane resistance of 980 ohms cm² was calculated on the assumption that the cells are discrete, 100 µ long and 6 µ in width, and shaped like two cones base to base. Resistance measurements between two cell interiors less than 0.5 mm apart averaged 236.0 megohms. Since the double-cell resistance is twice the single-cell resistance, it is concluded that no low resistance pathways between cells exist. This finding is in agreement with electron micrographs showing transverse membranes across the intercellular connections. The implications of these resistance values are discussed relative to propagation, methods of recording, and the nature of the "bioelectric generator."