Mechanism of Change in Permeability in Living Membranes

Abstract

AN important feature of many excitable cells is that their permeability to ions and even to large molecules such as aldolase depends on the potential difference across the cellular membrane¹. Thus, in nerve fibres a depolarization leads to a transitory increase in sodium permeability (P _Na), often followed by a slower development of an increase in potassium permeability (P _K). More recent studies of skeletal^2,3 and cardiac (Carmeliet, E., and Weidmann, S., personal communication) muscle have demonstrated an opposite relation between P _K and membrane potential that has been designated ‘anomalous rectification’. The purpose of this communication is to point out the possibility that the mechanism of these changes in permeability may be related to that recently proposed on the basis of monomolecular film studies of drugs known to affect the ionic permeability of natural membranes^4–6. This mechanism is based on recently demonstrated physico-chemical principles and is susceptible to experimental test.