Effects of Russell's viper venom on human erythrocytes in vitro.

The effects of Russell's viper venom (RVV) on human erythrocytes were studied in vitro with respect to packed cell volume (hematocrit), the erythrocyte morphology, and the effect of antivenom. Venom at various dosages ranging from 50 ng to 120 micrograms increased hematocrit significantly. The maximal effect was detected at 800 ng of venom. The biconcave erythrocytes shown by scanning electron microscopy became sphero-echinocytes. Such altered morphology was observed immediately at 1 minute and reached maximum at 30 minutes. The mild degree of erythrocyte deformation was observed at 60 and 120 min with 100 ng of RVV. There were no morphologic changes when ethylenediaminetetracetate (EDTA) was used as an anticoagulant or when plasma was substituted by isotonic saline, acetar, albumin added acetar solution. Phospholipase A2 at equivalent dose as compared to the venom could also produce the sphero-echinocytosis. The phospholipase A2 inhibitor, p-bromophenacyl bromide markedly reduced the degree of RVV induced sphero-echinocytosis. Verapamil, a phenylalkylamine calcium channel blocker, could not prevent the RVV induced sphero-echinocytosis. Although antivenom could not reverse the RVV induced sphero-echinocytosis, it minimized these effects. The RVV induced sphero-echinocytosis is likely caused by phospholipase A2. Calcium and some plasma factors are required for this process. Early treatment with antivenom plays some role in prevention of RVV induced sphero-echinocytosis which may reduce hypoxic cell injury.