II. Erythrocyte membrane stabilization by local anesthetics and tranquilizers

Abstract

1. Low concentrations of the local anesthetics dibucaine HCl and tetracaine HCl protect or stabilize human erythrocytes against hypotonic hemolysis; higher concentrations elicit a detergent hemolysis. Lidocaine HCl and procaine HCl also cause these biphasic effects but at higher extracellular pH. 2. Increasing the extracellular pH enhances the membrane-stabilizing and lytic potencies of these local anesthetics as well as those of the phenothiazine tranquilizers. 3. Decreasing the intracellular pH also enhances the stabilizing and lytic potencies of these tertiary amines. 4. Measurements of the circumferences of the erythrocyte profiles from electron micrographs indicate that 1.4 × 10 −5M prochlorperazine induces a membrane expan- sion of around 19 per cent. This expansion is compatible with an intramembrane location of the 10 8 molecules per cell that is known to occur (from adsorption studies).