Adrenaline and noradrenaline excretion in placebo treated patients in the Medical Research Council Hypertension Trial and in matched normotensive controls.

The 24-h excretion of adrenaline and noradrenaline was measured in 268 untreated essential hypertensives and in 268 age- and sex-matched controls. No significant difference was found between the groups. However, in the control group alone, a multiple regression analysis showed a highly significant correlation between systolic blood pressure and both noradrenaline (P = 0.0006) and adrenaline (P = 0.0001). These results suggest that any role for elevated sympatho-adrenal activity in long-term blood pressure regulation is limited to the time before hypertension is established.