The effect of chlorpromazine on cell membrane resistance and capacitance.

Chlorpromazine, at concentrations of 1-50 micron, caused rises of up to 10 mV in the p.d. across the isolated frog skin and decreases as great as 5% in membrane capacitance; at concentrations of 10 micron and above the resistance decreased, by up to 25%. Effects on p.d. and resistance were obtained only when the drug was added to the solution bathing the outside of the skin; these effects are possibly caused by increases in the sodium permeability of the outer membrane. The decrease in capacitance is not consistant with an increase in membrane area without changes in thickness or permittivity, but could be explained by a loss of water from the membrane.