1. Baroreceptor sensitivity and vascular reactivity to noradrenaline were assessed in patients with essential hypertension chronically treated with diuretics during treatment and 6–8 weeks after its withdrawal.
2. Stopping diuretics was followed by an increase in mean arterial blood pressure and vascular reactivity, while baroreceptor sensitivity decreased.
3. Baroreceptor sensitivity during treatment correlated directly with the time during which patients remained normotensive after stopping diuretics.
4. An inverse correlation was found between vascular reactivity and baroreceptor sensitivity after diuretic withdrawal and between the patients' age and baroreceptor sensitivity during diuretic therapy.
5. We conclude that the impairment of baroreceptor sensitivity after stopping diuretic therapy could result in an enhanced vascular response to noradrenaline, and a sensitive baroreflex could contribute to the control of blood pressure during diuretic treatment and buffers the return of high blood pressure when diuretics are stopped.