Determination of serum paraoxonase phenotype distribution by double-substrate method in patients with coronary artery disease

Considering the high incidence of patients with coronary artery disease [CAD] in the Iranian population and a preventive role of serum paraoxonase [PON1] in development of CAD, the present study was designed to determine the distribution of PON1 phenotypes in patients with CAD. A total of 61 patients with coronary stenosis of <50% and 63 patients with coronary stenosis of >70% were included in this study. Paraoxonase and arylesterase activities were measured using paraoxon and phenylacetate as substrate, respectively. Phenotyping of the PON1 Q192R polymorphism was determined by calculating the ratio of salt-stimulated paraoxonase activity to arylesterase activity [double-substrate method]. Patients with stenosis of <50% were separated into three distinct phenotypes at ratios of 2.14 and 5.99 and the population with stenosis of >70% at ratios of 2.42 and 5.91. In patients with stenosis of <50%, PON1 phenotype frequencies were 41% [Q phenotype], 46% [QR phenotype] and 13% [R phenotype]. Frequencies of Q, QR and R phenotypes in patients with stenosis of >70% were 48%, 41% and 11%, respectively. Based on this study and other studies conducted in Iran, it can be concluded that in the Iranian population there is no statistically difference in phenotype distribution of PON1 between patients with CAD [with severe stenosis or mild stenosis] and healthy individuals

Association between paraoxonase-1 activity and the extent of coronary stenosis

Paraoxonase [PON1] can prevent oxidized low-den sity lipoprotein formation and development of atherosclerotic lesions. However, studies on the association between PON1 activity and the extent of coronary stenosis and underlying mechanism[s] are limited. In this study, the relationship between paraoxonose and arylesterase activities of PON1 with extent of coronary stenosis together with determination of PON1 phenotypes in the studied have been investigated. Paraoxonase and arylesterase activities were measured in 61 patients with coronary stenosis of 50% and 63 Patients with coronary stenosis of 70% Individual human serum phenotype for the PON1 Q192R polymorphism was achieved through dividing the Paraoxonase activity in the presence of IM NaCL by arylesterase activity. Patients with stenosis of 50% had significantly higher PON1 activity [p0.05] and HDL-Cholesterol [p 0.03] compared to those with stenosis of 70%. No significant difference [p 0.05] was observed in the phonotype distribution of males and females. According to the current study, there are significant differences in paraoxonase and arylesterase activates and also HDL-C levels between patients with coronary stenosis of 50% and those with coronary stenosis of 70% therefore, this study provides further support for the important role of paraoxonase activity in coronary atherosclerosis