Changes in blood viscosity following nifedipine administration and its relation to the contents of adenosine triphosphate and 2,3-diphosphoglyceric acid in red blood cells in patients with angina pectoris

Abstract

The effect of oral administration of nifedipine (Adalat) on whole blood viscosity in patients with angina pectoris was investigated. Whole blood viscosity at a low shear rate of 37.5 s-1 was significantly reduced from 7.90 +/- 0.18 cP to 7.30 +/- 0.27 cP (1 cP = 1 mPa x s) after nifedipine administration (p less than 0.01), though the value at the high shear rate of 375 s-1, Casson yield stress value and Casson viscosity hardly decreased. Content of adenosine triphosphate (ATP) and 2,3-diphosphoglyceric acid (2,3-DPG) in the erythrocytes affecting blood viscosity, especially low shear rate viscosity, showed little change, and the hematocrit value was little varied either. Nifedipine, a Ca antagonist, has been known to inhibit Ca entry into the cells. These findings suggest that nifedipine reduces whole blood viscosity, especially low shear rate value, due to inhibition of Ca entry into the red blood cells, without increasing metabolic changes of ATP or 2,3-DPG in the erythrocytes, though measurement of Ca content in erythrocyte was unsolved.