Effects of ketanserin on the intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal male subjects.

The effect of acute and short-term administration of ketanserin on the intracellular concentrations and transmembrane fluxes of sodium and potassium was studied in erythrocytes of 12 sodium-replete normal male subjects. The subjects received 40 mg ketanserin three times a day for 1 week. Blood samples were drawn before and 1.5 h after the first dose, 12 h after the evening dose of the 6th day, and 1.5 h after the morning dose of the 7th day. The intraerythrocyte sodium concentration was not changed after the first dose of ketanserin, but was decreased during short-term treatment with ketanserin. The ouabain-sensitive 86Rb-uptake, an estimate of the Na+,K+-adenosine triphosphatase pump activity, was decreased after acute ketanserin administration, but not during short-term treatment. This change in intraerythrocyte sodium concentration was related to the change in ouabain-sensitive 86Rb-uptake. The red cell Na+,K+-cotransport and Na+,Li+-countertransport transport activity were not changed during acute and short-term administration of ketanserin. These results indicate that short-term ketanserin administration decreases the intraerythrocyte sodium concentration, but the flux measurements can not explain this observation.