Modification of membrane properties of erythrocytes by PGI2

The addition of prostaglandin I2 (PGI2) enhanced the adhesion of red cells from normals and patients with diabetes mellitus or sickle cell anemia (SCA) to human cultured endothelial cells (p less than 0.025). The maximal effect was reached with 10(-11) M PGI2 after 30 min incubation. Red cell adhesion was also increased by PGD2 but PGE1 and 6-keto-PGF1 alpha had no significant effect. Since enhanced adhesion of red cell to endothelium and increased red cell calcium content have been proposed to be related in SCA, we have investigated the calcium binding to human resealed normal erythrocyte membrane by using (45Ca) calcium in presence of the different PG which alter red cell adhesion or not. Calcium binding was time-dependent and potentiated in presence of PGI2 (p less than 0.01) but not of PGD2. The fact that erythrocyte adhesion is enhanced by both PGI2 and PGD2 while calcium binding is increased only by PGI2 suggests that the two phenomenon can be dissociated.