Ketanserin and red blood cell sodium content in hypertension

The sodium content of erythrocytes from patients with essential hypertension is increased. In a double-blind, placebo-controlled study, a 5-day treatment with ketanserin, a serotonergic antagonist lowered significantly the sodium content of the red blood cells (RBC). Ouabain induces an increase of sodium content of the RBC, which is paralleled by a decrease in RBC deformability. The ouabain-dependent fraction of RBC deformability is significantly reduced after a single oral dose of ketanserin. In vitro, serotonin (5-HT) decreases RBC deformability; this effect could be antagonized by ketanserin. These data might suggest a regulating role of 5-HT in transmembrane ion fluxes.