Free oxygen radicals or reactive oxygen species are accepted to have an active role in the patogenesis of coronary artery disease. Thirty five patients with coronary artery disease including 10 women and 25 men were enrolled in this study performed in order to determine the activities of catalase (CAT) and carbonic anhydrase (CA) in patients with coronary artery disease. Control group included 33 individuals, seven women and 26 men, with normal angiograms. CAT and CA enzyme activities in red blood cell samples of patients and control subjects were measured with spectrophotometry (with Aebi method) and carbon dioxide hydration method, respectively, and compared statistically. CAT values were 13.09±4.74 EU/gHb and 21.30±17.99 EU/gHb-1 and CA enzyme activities were 0.75±0.28 EU/gHb and 2.06±0.24 EU/gHb in patients with coronary artery disease and control subjects, respectively. The erythrocyte CAT and CA enzyme activities in the patient group were statistically significantly lower than those of the control group (p=0.015, p<0.001). It may be concluded that acid-base balance in the erythrocytes is disordered with the decreasing CA enzyme activities of patients with coronary artery disease. The lower levels of CAT enzyme activity which is a protective enzyme against free radical damage may be due to the oxidative stress from which the patients suffered, and manipulations toward erasing this stress may be effective in the prevention and treatment of the disease.

Keywords: Erythrocyte, carbonic anhydrase, catalase, coronary artery disease