EFFECTS OF RENAL CYTOPROTECTIVE AGENTS ON ERYTHROCYTE-MEMBRANE STABILITY

To elucidate potential mechanisms of ischemic renal injury, investigat ors often use drugs that interfere with specific pathological pathways and study their protective efficacy in in vitro models of ischemia, s uch as isolated renal proximal tubules subjected to hypoxia. However, the protective effects of certain drugs may depend on non-specific mem brane stabilizing properties. We have studied the effects of several d rugs on membrane integrity using osmotic lysis of erythrocytes as a mo del system. Freshly isolated rabbit erythrocytes were subjected to a h ypotonic shock, and the protective effects of various calcium channel blockers, phospholipase inhibitors, free fatty acids, the NO-synthase inhibitor L-NAME, the amino acid glycine and its receptor-analogue str ychnine, and two chloride channel blockers were examined. Most agents protected erythrocytes against hypotonic hemolysis when added to the m edium in the same concentration range as used in suspensions of hypoxi c proximal tubules. Only the protective agents that proposedly act via a blockade of chloride influx (glycine, strychnine and the chloride c hannel blockers), did not attenuate hypotonic hemolysis. The erythrocy te hemolysis assay may provide an easy and rapid method to screen for non-specific membrane-stabilizing effects of potentially cytoprotectiv e agents.