Effect of pentoxifylline on red cell flexibility and cation transport in healthy subjects and patients with hereditary spherocytosis.

The effect of pentoxifylline (3,7-dimethyl-1-(5-oxo-hexyl)-xanthine) on the flexibility of red cells was studied using a filtration method in which the red cells are forced, at a constant flow-rate, through a porous polycarbonate membrane. The filtration pressure reflects red cell rigidity and the amount of Hb released from the disrupted cells ('free Hb') red cell fragility. The advantage of this method is that it allows the two important determinants of red cell flexibility, rigidity and fragility, to be studied simultaneously. Pentoxifylline significantly improved normal red cell flexibility both in vivo and in vitro as judged by this method. The impaired flexibility of red cells from patients with congenital or hereditary spherocytosis (HS) was aggravated by pentoxifylline in vitro. A similar effect of pentoxifylline was also observed on red cells from relatives of HS patients. The effect of pentoxifylline on Ca2+ transport and Ca2+-Mg2+-ATPase activity in red cells from normal and HS patients was investigated. Under in vitro conditions pentoxifylline did not affect the Ca2+-Mg2+-ATPase activity of or Ca2+ efflux from normal and HS red cells. Neither the influx of monovalent cations (Na+, Rb+) or the osmotic resistance of normal or HS red cells was affected by pentoxifylline.