In Vitro influence of some local anaesthetics on the surface electrical properties of erythrocytes

ABSTRACT

Four molecules [Procaine, Tetracaine, Bupivacaine and Lidocaine] of either the ester or amide type of local anesthetics were studied. Erythro-cytes were used to provide the membrane model. The surface electrical properties were determined by the electro-rotation technique. It was found that the surface conductance, Ks was the most sensitive parameter, while the membrane capacity [CM] refractory to treatment with the local anesthetics tested. The values for Ks decreased with the increase in the concentrations of the local anesthetics giving concentration-response relationships. The values of the EC50 were found to be in the following order Tetracaine [22.63 nM] > Bupivacaine [45.91] > procaine [59.57 nM] = Lidocaine [59.73 nM]. The values were inversely proportional with lipid/water partition coefficients of the respective molecules