Association of paraoxonase activity and coronary blood flow

Paraoxonase (PON) is a high-density lipoprotein-bound anti-oxidant enzyme that inhibits atherosclerosis and endothelial dysfunction. Slow coronary flow (SCF) has long been identified and endothelial dysfunction and atherosclerosis of epicardial coronary arteries and microvasculature were reported to be associated with SCF. Consequently, we aimed to investigate the association between coronary blood flow by means of Thrombolysis in Myocardial Infarction frame count (TFC) and serum PON activity and other laboratory parameters in patients with SCF compared to control cases.

Twenty-four patients with SCF and 110 control cases with normal coronary flow were studied after quantifying coronary blood flow according to TFC. Serum PON activity was evaluated by measuring the rate of paraoxon hydrolysis. The association between TFC and serum PON activity and other clinical and laboratory parameters were evaluated.

There were statistically significant differences between SCF and control groups in respect to serum uric acid (p=0.001), high sensitive C-reactive protein (p=0.03) levels and serum PON activity (p<0.001). The mean TFC was correlated with male gender (r=0.263, p=0.002), serum uric acid level (r=0.287, p=0.001), hemoglobin concentration (r=0.192, p=0.032) and serum PON activity (r=-0.306, p<0.001). Serum uric acid level (chi(2)=10.08, beta=0.362, p=0.009) and serum PON activity (chi(2)=16.73, beta=-0.005, p=0.001) were independent predictors of SCF whereas the only independent predictor of mean TFC was serum PON activity (beta=-0.318, p<0.001).

These findings suggest that serum PON activity is independently associated with mean TFC and reduced serum PON activity might represent a biochemical marker of SCF.