P-302: Dopaminergic modulation on the cardiovascular responses in hypertensive subjects

Dopamine (DA), a neurotransmitter, precursor of noradrenaline, is responsible for cardiovascular and renal actions, such as increase in myocardial contractility and cardiac output, without changes in heart rate, producing passive and active vasodilatation, diuresis and natriuresis. These cardiovascular and renal actions take place through the interaction with dopamine receptors, D1, D2, D3, D4, and D5. Dopamine is known to influence the control of arterial pressure by influencing the central and peripheral nervous system and target organs such as kidneys and adrenal glands, in some types of hypertension. Although dopamine and its derivatives have been shown to have antihypertensive effects, these are still being studied; therefore it is important to explain some physiological and pharmacological aspects of dopamine, its receptors and the clinical uses it could have in the therapy of arterial hypertension. In previous studies we have demonstrated the role of DA in the insulin secretion, renal circulation and respiratory function. We have studied 10 (ten) hypertensive patients under the following experimental design: 1) placebo with 5% glucose solution during a 30 min period, 2) Metoclopramide (MTC) a DA2 dopamine blocker, at the intravenous dose of 7,5 mg/Kg/min during a 30 min period, and 3) Dopamine at the intravenous dose of 1 μg/kg/min added to the metoclopramide infusion, during a 30 min period. MTC decreased blood pressure and heart rate significantly beginning 5 min drug infusion. When dopamine was added to MTC infusion, there was an additional decrease of blood pressure without any alteration of heart rate. We conclude that: 1) There is a dopaminergic modulation during cardiovascular responses, 2) Both drugs MTC and DA act as antihypertensive agents of potential usefullness in the therapy of hypertension. Am J Hypertens (2004) 17, 142A–142A; doi: 10.1016/j.amjhyper.2004.03.377