Diamide decreases deformability of rabbit erythrocytes and attenuates low oxygen tension-induced ATP release

Abstract

Exposure of erythrocytes to reduced oxygen (O2) tension activates the heterotrimeric G-protein Gi, resulting in the accumulation of cyclic AMP (cAMP) and release of ATP. The mechanism by which exposure of erythrocytes to reduced O2 tension activates Gi is not known. Here we investigate the hypothesis that, in rabbit erythrocytes, ATP release in response to exposure to reduced O2 tension is linked to erythrocyte membrane deformability. If this hypothesis is correct, then decreasing the deformability of the erythrocyte membrane should decrease the release of ATP in response to reduced O2 tension. We report that treating erythrocytes with diamide, a compound that decreases erythrocyte deformability, inhibits low O2 tension-induced ATP release. Treating erythrocytes with diamide does not, however, interfere with cAMP accumulation or ATP release in response to a direct activator of Gi (mastoparan 7) or in response to receptor-mediated activation of Gs (the prostacyclin analog, iloprost). These results demonstrate that diamide (100 μmol/L) does not directly inhibit the signaling pathways for ATP release from rabbit erythrocytes and support the hypothesis that low O2 tension-induced ATP release from these cells is linked to membrane deformability.