MECHANISM OF THE CHANGE IN SHAPE OF HUMAN ERYTHROCYTES INDUCED BY LIDOCAINE

We studied the mechanism of the lidocaine-induced shape change in huma n erythrocytes. Immunohistochemical analysis of erythrocytes using spe ctrin-specific antibodies revealed aggregation of fluorescence in lido caine-treated cells, while the fluorescence was distributed diffusely in untreated cells. The intracellular pH in lidocaine-treated erythroc ytes was examined by flow cytometry of the cells labeled with 2'-carbo xyethyl-6',7'-(dihydropyran-2'-one)-5-carb diacethoxymethylester (BCEC F-AM), and was found to decrease with increasing concentrations of lid ocaine. Pre-treatment of erythrocytes with acetazolamide, an inhibitor of carbonic anhydrase, inhibited the lidocaine-induced spectrin aggre gation and decrease in intracellular pH. When erythrocytes were incuba ted in medium containing bafilomycin A(1), an inhibitor of V-ATPase, f ollowed by incubation with lidocaine, the cells changed shape slightly and the intracellular pH showed a small decrease in comparison with c ontrol. Spectrin dimers extracted from membranes of normal erythrocyte s were incubated in buffers of various pHs and analyzed by SDS-PAGE. T he amounts of spectrin dimers and tetramers decreased, while that of o ligomers increased with decreasing pH. These results suggest that the lidocaine-induced shape change in human erythrocytes may occur by the conformational change of spectrin in a process that may be mediated by carbonic anhydrase and activation of V-ATPase.