Immersion of one hand into ice water (cold pressor test) in eight hypertensive subjects induces elevation of mean arterial pressure, increase in heart rate, and no significant changes of plasma renin activity and plasma aldosterone concentrations. Domperidone, a DA2 dopaminergic antagonist, attenuates heart rate increase induced by the cold pressor test, and the combination of bromocriptine, a known DA2 dopaminergic agonist, with domperidone again provoked a heart rate increase during the cold pressor test. Domperidone caused an increase of both plasma renin activity and plasma aldosterone concentrations, which were reversed by bromocriptine. These results suggest that a dopamine-receptor stimulation is taking place during the cold pressor test.