The pressor effect of exogenous angiotensin II is diminished during dynamic exercise

To evaluate the effect of dynamic exercise on the response to angiotensin II (AII), AII (7.5 ng/kg/min) or vehicle (P) was infused intravenously in seven normal sodium replete volunteers before, during and after a graded uninterrupted exercise test until exhaustion, using a randomized cross-over protocol. Plasma angiotensin II (PAII) during AII infusion was an average 86-145 pg/ml higher than during P. The differences in mean intra-arterial pressure between the AII and the P tests averaged 17 mmHg at recumbent rest, 12 mmHg in the sitting position on the bicycle ergometer and 7 mmHg at 20% of peak work rate declining progressively throughout the exercise test to become insignificant from 80% of peak work rate on. A significant difference reappeared after exercise. It is suggested that the powerful vasoconstriction in some vascular beds and the dilatation in others oppose the vasoconstricting effect of AII; other possible mechanisms are changes in pH and a decrease of the difference in log PAII between the AII and P tests with increasing levels of endogenous PAII during exercise.