INCREASED RIGIDITY OF RED-CELLS IN PATIENTS WITH PLASMODIUM-FALCIPARUM AND ITS POSSIBLE RELATION TO CEREBRAL MALARIA

The rheological parameters which indicated the rigidity of red cells, i.e., Red cell internal viscosity (eta(i)) and plasma trapping were de termined in patients infected with Plasmodium falciparum and were comp ared to that of normal subjects. Plasma trapping was determined and th is value is used for packing coefficient (k). There was an increase in plasma trapping in patients which indicated an increase in rigidity o f their red cells. The internal viscosity of red cells (eta(l)) were d etermined by the blood viscosity equation :eta(r) = (1-kCT)(-2.5) whic h was proposed by Dintenfass in 1968. Although blood viscosity (eta(b) ), plasma viscosity (eta(p)) and relative viscosity (eta(r)) of the ma larial patients were significantly less fhan that of normal subjects, the actual volume concentration of red cells (C = Hct/k) of these pati ents were also significantly less than that of normal subjects. And it was found that the mean Tk value of the patients was significantly hi gher than that of normal subjects. Since T is equal to (P + 0.4)/(p 1), where p is eta(l)/eta(p), then the eta(l) of the patients were sig nificantly higher than that of the normal subjects. These findings lea d us to postulate that increased rigidity of the red cells is behind t he mechanism of vascular obstruction in patients with cerebral malaria .