Hemolitik mekanik travmaya maruz bırakılan eritrositlerde nitrik oksidin ve potasyum kanal blokajının koruyucu etkisi

Shear forces effective in the normal mammalian circulatory system remain below the hemolytic threshold. However, mechanical trauma to red blood cells (RBC) during blood flow through artificial organs or extracorporeal circuits may exceed this threshold and results in hemolysis. It has been previously demonstrated that nitric oxide and potassium channel blockage play a protective role in non-hemolytical mechanical trauma to RBC. This study was designed to test if this protective effect can also be observed in hemolytic mechanical trauma to RBC. Heparinized venous blood samples were obtained from ten healty, adult donors. The hematocrits of all blood samples were adjusted to 0.4 L/L by recombining the packed RBC and outologus plasma and divided into five groups; Control, mechanical stres (MS), M.S.+Sodium nitroprussid (SNP), M.S.+Tetraethylammonium (TEA) and M.S.+Clotrimazole (CLT). M.S.+SNP, M.S.+TEA and M.S.+CLT groups were incubated in room temparature for 1 hour with SNP (10-4 M), TEA (10-7 M) and Clotrimazol (3X10-5 M) respectively. After incubation, blood samples from mechanical stres groups were pumped through a glass capillary (diameter= 0.06 cm; length= 33 cm) using a roller pump, to maintain a pressure gradient of 200 mmHg, for 30 minutes. At the end of the mechanical stres application, hemolysis ratio, RBC deformability and whole blood cell count were measured and cell morphology was analysed. Although the calculated wall shear stress within the capillary tube was below hemolytical threshold, 30 minutes flow of blood under these circumstances result in about 3% hemolysis monitored by the measurement of plasma hemoglobin. A series of 10 experiments revealed that the degree of hemolysis was not affected by including SNP, TEA or clotrimazole in the blood sample. Besides that, mechanical stress application did not cause significant alterations in RBC deformability or cell morphology. In conclusion, as the calculated shear stress in the capillary tube in the system was below the hemolytical threshold, the hemolysis was caused mainly by the roller pump used in the system. The findings of the present study showed that neither nitric oxide nor potassium channel blockage could prevent this mechanical damage. Key words: Shear stress, mechanical trauma, hemolysis, nitric oxide