Effects of drugs on calcium-related phenomena in red blood cells.

Red blood cells (RBCs) keep their internal Ca concentration at a low level by virtue of their limited Ca permeability and a potent, ATP-dependent system for Ca extrusion. Cytoplasmic Ca concentrations can be raised by in vitro procedures such as ATP depletion or the use of certain ionophores. High-Ca cells prepared by these means demonstrate a number of interesting morphological, physical, and biochemical changes. Some of these phenomena can be influenced by drugs, usually in suprapharmacological concentrations. The potential importance of these observations for the treatment of hemolytic or microcirculatory disorders is uncertain, inasmuch as the role of Ca in modifying the properties of RBCs in vivo is not clear.