Dopaminergic influence on the cardiovascular response to exercise in normotensive and hypertensive subjects

Fourteen subjects (normotensive, hypertensive) were studied at the Vargas Hospital of Caracas. They were treated with placebo (2 periods), domperidone, a peripheral dopaminergic blocker, at the daily oral dose of 40 mg, and metoclopramide, a central and peripheral dopaminergic blocker, at the daily oral dose of 40 mg. All placebo and active drug periods lasted 1 week. Cardiovascular hemodynamic parameters (blood pressure, heart rate) were measured before, during and after submitting subjects to treadmill exercise according to the Bruce's protocol. Metoclopramide decreased significantly heart rate before and during exercise stress and systolic blood pressure during stage 1 exercise in normotensive subjects. Domperidone decreased significantly heart rate before and during exercise stress, and systolic blood pressure during stage 3 exercise in hypertensive subjects. Neither heart rate nor blood pressure were changed significantly after 8 minutes resting period post exercise. Our results suggest the existence of an excitatory modulatory influence of dopaminergic influence during exercise over the sympathetic activity.