[Influence of homologous n-alkanoic on functional properties of isolated skeletal muscles. II. Membrane resting potential and the osmotic effectiveness of alkanoic acid].

The influence of butyric, hexanoic, octanoic, and decanoic acid on the membrane resting potential of isolated frog skeletal muscles were studied and the osmotic effects of n-alkanoic acids tested. 1. n-alkanoic acids cause osmotic effects like impermeable non-electrolytes (sucrose). Therefore, the permeability to alkanoic acids of the resting muscle cell membrane seems to be small. There are no differences between the acids tested. 2. The membrane resting potential is differently affected. Butyric acid in high concentration effects a hyperpolarization of the membrane whereas higher homologues (C6--C10) cause a depolarization. The depolarizing action increases with increasing concentration, exposure, and with the length of the hydrocarbon chain of the alkanoic acids. 3. It is suggested that osmotic effects are the cause for hyperpolarization of the membrane by high concentrations of butyric acid. 4. The depolarizing action of hexanoic, octanoic, and decanoic acid is discussed with regard to alterations induced by alkanoic acids in the membrane permeability and/or in the metabolism of the cells.