LOW-DENSITY-LIPOPROTEIN OXIDATION, AND VITAMIN-E AND VITAMIN-C IN SUSTAINED AND WHITE-COAT HYPERTENSION

Low-density lipoprotein oxidation and antioxidant vitamins E and C wer e investigated in white-coat hypertension in comparison with sustained hypertension and normotension. We selected 21 sustained hypertensive subjects, 21 white-coat hypertensive subjects, and 21 normotensive sub jects matched for gender, age, and body mass index. White-coat hyperte nsion was defined as clinical hypertension and daytime ambulatory bloo d pressure <139/90 (subjects were also reclassified using 134/90 and 1 35/85 mm Hg as cutoff points for daytime blood pressure). Blood sample s were drawn for lipid profile determination, assessment of fluorescen t products of lipid peroxidation in native LDL, evaluation of suscepti bility to LDL oxidation in vitro (lag phase and propagation rate), and determination of LDL vitamin E: and plasma vitamins E and C contents. Compared with sustained hypertensive subjects, white-coat hypertensiv es had significantly lower fluorescent products of lipid peroxidation (15.4+/-3.4 versus 10.2+/-3 units of relative fluorescence/mg LDL prot ein, P<.05), longer lag phase (54+/-10 versus 88+/-10 minutes, P<.05), lower propagation rate (8.2+/-2.5 versus 5.95+/-2.1 nmol diene/min pe r mg LDL cholesterol, P<.05), higher LDL vitamin E content (8.3+/-1.1 versus 10.1+/-1.8 nmol/mg LDL cholesterol, P<.05), and plasma vitamin C content (40+/-13 versus 57+/-9 mu mol/L, P<.05). No significant diff erence was observed between white-coat hypertensive and normotensive s ubjects. The results did not change after reclassification of subjects . Our data show that white-coat hypertensive subjects do not show an e nhanced propensity to LDL oxidation or reduction in antioxidant vitami ns. Given the role oi LDL oxidation in the development of atherosciero sis and that of vitamin E and C in protecting against it, these findin gs suggest that white-coat hypertension per se carries a low atherogen ic risk.