Effects of nitric oxide and prostacyclin on deformability and aggregability of red blood cells of rats ex vivo and in vitro

Although many diseases of the heart and circulatory system-have been linked with insufficient deformability and increased aggregability of red blood c ells, there are only a few drugs which can modulate these biological functi ons of erythrocytes. Here, we show evidences that iloprost, stable prostacy clin analogue and SIN-1, active metabolite of molsidomine which spontaneous ly releases NO, may be sufficient pharmacological tools for modulating red blood cell deformability and aggregability. Deformability of red blood cell s was measured by, shear stress laser diffractometer (Rheodyn SSD) and expr essed in percent of red blood cell deformability index (DI). MA-1 (Myrenne) erythrocyte aggregometer was used for photometric measurements of aggregab ility in arbitrary units (MEA) of mean extent of aggregation. Experiments w ere carried out on rats el,vivo and:in vitro using whole rat blood or isola ted erythrocytes. Ex vivo SIN-1 (infusion 2 mg/kg/min i.v.) and iloprost (b olus injection 10 mu g/kg i.v.) significantly improved erythrocyte deformab ility and aggregability at 5-15 min after administration. L-NAME (10 mg/kg i.v.) -inhibitor of nitric oxide synthase, and aspirin (1 mg/kg i,v.) cause d worsening of deformability of erythrocytes In experiments ex vivo. Studie s in vitro also revealed improvement of red blood cell deformability and ag gregability by SIN-1 (3 mu M, 15 min incubation at 22 degrees C) or ilopros t: (1 mu M,: 15 min incubation at 22 degrees C) and this phenomenon appeare d not only in whole blood but also in isolated red cells. It is concluded t hat NO- and prostacyclin-induced improvement of red blood cell deformabilit y and aggregability results from direct action of these compounds on erythr ocytes. NO-donors and iloprost-could,;be useful in the treatment of disorde rs of blood fluidity.