Effect of intravenous dopamine on blood pressure and plasma insulin in hypertensive patients.

Eleven patients with moderate to severe hypertension were pre-treated with oral labetalol 800-1200 mg/day for one week, prior to receiving two i.v. infusions of dopamine 1-3 micrograms/kg/min each of 30 min each, before and after the i.v. bolus injection of metoclopramide 30 mg. There were washout periods before and after the metoclopramide administration. Dopamine induced a significant decrease of blood pressure from 172/104 to 153/94 mm Hg without altering heart rate, and it increased the plasma insulin level from 8.3 to 12.1 microU.ml-1. Metoclopramide did not itself affect blood pressure or plasma insulin, but it did block the hypotensive response and rise in plasma insulin due to dopamine. We conclude that the pharmacological actions of intravenous dopamine on the cardiovascular system and on insulin secretion may be mediated by dopaminergic receptor stimulation.