Blunted nocturnal fall in blood pressure and oxidative stress in men and women with essential hypertension

Low-density lipoprotein oxidation:and antioxidant vitamins E and C were inv estigated in dipper (nocturnal blood pressure fall > 10%) and nondipper (no cturnal blood:pressure fall < 10%) hypertensives.: We studied 40 dippers an d 28 nondippers balanced for: gender, age, and body mass index. Blood sampl es were drawn for lipid profile determination, assessment of thiobarbituric acid-reactive substances, and fluorescent products of lipid peroxidation i n native low-density lipoprotein, evaluation of susceptibility to:low-densi ty lipoprotein oxidation in vitro (lag phase and propagation rate), and det ermination of low-density lipoprotein vitamin E and plasma vitamins E and C contents. Compared with dippers, nondippers had significantly higher thiob arbituric acid-reactive substances and fluorescent products of lipid peroxi dation (0.63 +/- 0.1 v 0.77 +/- 0.08 nmol malondialdehyde/mg low-density li poprotein protein, and 14.5 +/- 6 v 17.9 +/- 4 units of relative fluorescen ce/mg low-density lipoprotein protein, respectively, both P < .05), shorter lag phase (56 +/- 13 v 49 +/- 9 min, P < .05), and;lower plasma vitamin C content (42 +/- 9 v 35 +/- 10 mu mol/L, P < .05). When gender was taken int o account, differences were not significant between dipper and nondipper me n, whereas, compared with dipper women, nondipper women showed significantl y higher thiobarbituric acid-reactive substances and fluorescent products o f lipid peroxidation (0.56 +/- 0.1 v 0.77 +/- 0.07 nmol malondialdehyde/mg low-density lipoprotein protein, and 12.5 +/- 4 v 17.5 +/- 4.6 units of rel ative fluorescence/mg low-density lipoprotein protein, respectively, both P < .05), shorter lag phase (62.5 +/- 11 v 49 +/- 9.5 min, P < .05), and low er plasma vitamin C content (44.9 +/- 10 v 34.7 +/- 10.8 mu mol/L, P < .05) , Given the role of low-density lipoprotein oxidation in the pathogenesis o f atherosclerosis and that of vitamin C in protecting against it, our data suggest that nondippers, especially among women, show higher atherogenic ri sk than dippers. (C) 1999 American Journal of Hypertension, Ltd.