Vasoconstrictor effects of angiotensin II on the pulmonary vascular bed.

The systemic pressor effects of angiotensin II (ANGII) are well described, whereas relatively little is known regarding its effects on the pulmonary circulation in humans. Doppler echocardiographic measurements were performed in eight normal volunteers after a 30-min control infusion (baseline), after sequential 30 min stepwise infusions of ANGII (2, 4, and 6 ng/kg/min), and again 30 min after stopping ANGII therapy. There were significant dose-related increases in mean pulmonary arterial pressure and total pulmonary vascular resistance, with values returning to baseline after stopping ANGII therapy. However, the increase in vascular resistance was proportionately greater for the pulmonary compared with systemic vascular bed, and the difference was significant at all doses of ANGII. Thus, the pulmonary vasculature exhibited greater sensitivity to the vasoconstrictor effects of ANGII in comparison with the systemic vasculature.