MEMBRANE EXPANSION OF INTACT ERYTHROCYTES BY ANESTHETICS

1. 1. Low concentrations of the alcohol and phenothiazine anesthetics protected human erythrocytes from hypotonic hemolysis. 2. 2. The reduction in osmotic fragility amounted to a shift of 0.03 g/100 ml NaCl in the presence of a concentration of anesthetic which reduced osmotic hemolysis by 50 %. 3. 3. The anesthetics protected erythrocytes against hypotonic hemolysis over a 1000-fold range in the rate of hemolysis. The drugs do not act by changing the rate of hemolysis. 4. 4. Albumin up to 5.6 % did not reduce the amount of the osmotic hemolysis. Albumin did shift the dose-response curve for chlorpromazine to higher concentrations but only slightly reduced the maximum amount of protection. 5. 5. Low concentrations of the anesthetics did not affect the volumes of the cells in isotonic and moderately hypotonic solutions (down to 0.35 % NaCl). 6. 6. The critical hemolytic relative volume, Vc, was measured by the Guest and Wing technique. The Vc obtained by a Coulter counter and computer method agreed with the Vc obtained using Van Allen hemotocrit tubes. The value for Vc in the absence of any anesthetics was 1.825 and the membrane area of the prehemolytic sphere was about 136 μ2. 7. 7. The anesthetics increased the Vc. At an anesthetic concentration which reduced osmotic hemolysis by 50 %, the Vc increased to 1.925; at 95 % reduction in hypotonic hemolysis the Vc went up to around 2.02. The corresponding membrane areas were around 141 and 149 μ2, respectively. at 50 % protection, therefore, the membrane area of the intact erythrocyte expanded by approx. 3 %. © 1969.