Improvement in arterial oxygenation by saralasin infusion in man

Simultaneous hemodynamic and blood gas measurements were performed in 26 hypertensive adults, who were cigarette smokers, before and after a 30-minute infusion of saralasin (5 microgram/kg/min) which is a highly specific competitive antagonist of angiotensin II (AII). The arterial pressure fell in nine, rose in seven and was unchanged in ten patients. The mean cardiac index for the entire group remained unchanged. Pulmonary arterial or wedge pressure, pulmonary vascular resistance, arterial PCO2 and pH did not change. Unrelated to the hemodynamic changes, the mean arterial oxygen pressure (PaO2) increased from 68.6 +/- 2.2 mm Hg to 73.9 +/- 2.1 mm Hg (P less than 0.001). In the absence of a significant increase in alveolar ventilation as indicated by an unchanged mean PCO2 and lacking a hemodynamic explanation, the mechanism for the rise in PaO2 is speculative at this stage. The possibility of an improvement in the distribution of ventilataion by saralasin infusion is under investigation.