Effect of positive family history of hypertension on the blood pressure and catecholamine responses to a 6 hour adrenaline infusion.

1. The effects of 6 h infusion of adrenaline (INF-A) or dextrose (INF-D) and of post-infusion cold pressor test (CPT) were compared in normal subjects, with (FH+) and without (FH-) a family history of hypertension. 2. Increased urinary excretion rates suggested facilitated noradrenaline (NA) release during and after INF-A in both FH+ and FH-. 3. Urinary adrenaline (UADR) excretion increased during INF-A, as expected, and was also slightly higher after INF-A than INF-D. 4. The effect of INF-A on systolic blood pressure (SBP) was greater in FH- than in FH+ but diastolic blood pressure (DBP) did not fall as quickly with nocturnal recumbency after INF-A in FH+. 5. A significantly greater response in plasma NA to CPT was seen in FH+ than in FH- after INF-A. A similar trend was also seen after INF-D. 6. Increases in DBP due to CPT were higher in FH+ than in FH- after both infusions. 7. This study provides evidence of increased noradrenergic activity during and after INF-A, and also of a difference in response to sympathetic stimulation between FH+ and FH-.