Paraoxonase and arylesterase activities in untreated dipper and non-dipper hypertensive patients

Paraoxonase, a high density lipoprotein (HDL) associated enzyme, was shown to be reduced in patients with cardiovascular diseases. We aimed to examine serum paraoxonase and arylesterase activities, and oxidative stress markers such as lipid hydroperoxide (LOOH) and total antioxidant status (TAS) in dipper and non-dipper hypertensive patients.

Forty-six non-dipper hypertensives (NDH group), 40 dipper hypertensives (DH group) and 28 healthy control subjects were included in the study. Clinical and echocardiographic assessment and ambulatory blood pressure monitoring were performed in all subjects. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by ferrous oxidation with xylenol orange assay. TAS was determined by using an automated measurement method.

Paraoxonase and arylesterase activities and TAS levels were significantly lower in patients with NDH compared to both DH and control groups (p<0.001, for both). Also, LOOH levels were found at high level in patients with NDH compared to control and DH groups. In NDH group, both paraoxonase and arylesterase activities were independently correlated with LDL cholesterol, TAS and LOOH levels. In DH group, both paraoxonase and arylesterase activities were independently correlated with HDL cholesterol and LOOH levels.

Reduced paraoxonase and arylesterase activities in NDH might indicate increased oxidative stress, which plays an important role in the development of cardiovascular diseases. Low serum activities of paraoxonase and arylesterase might be considered as prospective prognostic markers of the development of cardiovascular diseases in dipper and non-dipper hypertensive patients.