All Lipid-soluble Anaesthetics protect Red Cells

FOR the study of molecular events involved in the membrane action of anaesthetics, a cell is required which responds to all anaesthetics and which has a membrane that can be readily isolated. Erythrocytes may serve this purpose both qualitatively and quantitatively, for all lipid-soluble anaesthetics examined so far protect these cells from hypotonic haemolysis. Table 1 lists the anti-haemolytic concentrations of twelve different families of lipid-soluble anaesthetics including steroids¹, alcohols^2,3, tranquillizers⁴, fatty acids⁵, detergents^6,7, propranolol⁸, vasodilators⁹ and barbiturates¹⁰. Drugs which are highly water-soluble, on the other hand, do not protect erythrocytes from hypotonic haemolysis. Tetrodotoxin is a lipid-insoluble local anaesthetic and does not protect human erythrocytes; this compound, however, does not always anaesthetize excitable membranes¹⁸.