Rheological action of oxpentifylline and structurally related xanthine derivatives on human erythrocytes

Abstract

Erythrocytes from healthy adults and patients with homozygous sickle cell anaemia were treated in vitro with either the calcium ionophore A23187, the K⁺ ionophore valinomycin, or the Na⁺/K⁺ ionophore nystatin to induce loss of intracellular K⁺ and water. The dehydrated cells showed loss of filterability (deformability) through pores of 5 µm diameter. Xanthine derivatives possessing one or two long side chains (oxpentifylline, torbafylline [HWA 448] and A81 3138) showed a similar protective effect against loss of filterability at concentrations of 1, 10 and 100 µmol/l and 5 mmol/l. Theophylline (1,3-dimethylxanthine) showed no protective effect at 5 mmol/l. The presence of at least one long side chain on the xanthine moiety seems to be an important determinant of rheological activity, possibly by increasing binding to the erythrocyte membrane.