Plasma dopamine-beta-hydroxylase activity in oral contraceptive hypertension.

A prospective study was undertaken to evaluate the relative contribution of changes in sympathetic nervous system activity, as reflected by changes in dopamine-beta-hydroxylase (DBH) activity, to the pathogenesis of oral contraceptive-induced hypertension. Precontraceptive and serial post contraceptive determinations of blood pressure, plasma renin activity (PRA), DBH activity, and changes in body weight were obtained in twelve control patients and forty-one oral contraceptive users. Forty-four percent of oral contraceptive users had increases in blood pressure but remained normotensive and 17% became frankly hypertensive. The precontraceptive and average post contraceptive levels of mean arterial pressure (MAP), PRA and DBH activity in each patient were compared using paired group analysis. Control patients (group I) exhibited no significant changes in these variables, while the patients with contraceptive-induced increases in MAP (groups III and IV) underwent significant, parallel increases in DBH activity. Finally, the linear regression of changes in MAP on the percent change in DBH activity was examined. The positive slopes in groups III and IV differed significantly from the negative slope of the controls (group I). The data have been interpreted to reflect an inappropriate oral contraceptive-induced stimulus to sympathetic nervous system activity, leading to increases in MAP in susceptible individuals.