Cellular and humoral effects of naftopidil in man.
The effects of naftopidil on the intracellular concentration and transmembrane fluxes of Na+ and K+ in erythrocytes and on the intracellular Na+, K+ and free cytosolic Ca2+ concentration in platelets were studied in twenty-four normal male subjects, using a double-blind study design. After a run-in period on placebo for 1 week, the subjects were treated with either placebo (n = 8) or naftopidil 25 mg (n = 8) or 50 mg (n = 8) once a day for 4 weeks. Intraerythrocyte Na+ concentration and the erythrocyte anion carrier were decreased during naftopidil administration. No significant effect of naftopidil could be demonstrated on ouabain-sensitive Na+ efflux, bumetanide-sensitive Na+ efflux, ouabain, bumetanide-resistant Na+ and K+ efflux and Na+, Li(+)-countertransport activity in red blood cells or on the intraerythrocyte K+ and Mg2+ concentration. The free cytosolic Ca2+ and Na+ concentration in platelets was also decreased during naftopidil administration while no effect of naftopidil was found on the intracellular K+ and Mg2+ concentration in platelets.
Department of Pathophysiology, University of Leuven, Belgium.
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D000284:Administration, Oral; D000293:Adolescent; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D001792:Blood Platelets / Q000187:drug effects; D004573:Electrolytes / Q000097:blood*; D004910:Erythrocyte Membrane / Q000187:drug effects; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D008297:Male; D009281:Naphthalenes / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D004573:Electrolytes; D009281:Naphthalenes; D010879:Piperazines; C064357:naftopidil