In vitro effect of cilazaprilat on sodium-potassium transport systems in human erythrocytes

The in vitro effects of cilazaprilat in a concentration range of 10 nM to 1 mM were investigated on various Na+ and K+ transport systems in human red blood cells. Cilazaprilat inhibited the anion carrier or DIDS-sensitive LiCO3(-)-influx and the bumetanide-sensitive K(+)-efflux. However, no effect of cilazaprilat on the Na+, K(+)-pump activity, the number of active Na+ pump units and on the Na+, Li(+)-countertransport activity could be demonstrated. It is suggested that through a decreased anion carrier indicating a decreased Na(+)-influx, the lower intracellular Na+ concentration observed in vivo during angiotensin-converting enzyme inhibition, can be at least partly explained.