Atrial Natriuretic Peptide and its Possible Role in Post Exercise Hypotension

Abstract

The mechanisms which cause post exercise hypotension (a phenomenon of prolonged, decreased resting blood pressure following physical exertion) are unknown. Atrial natriuretic peptide (ANP) is known to exert potent natriuretic and vasodilatory properties which play an integral role in fluid regulation and blood pressure control. Elevations in plasma ANP concentration have been shown to occur during dynamic endurance exercise, and to a lesser extent during heavy resistance exercise. The purposes of this investigation were to 1) examine the effects of resistance and endurance exercise on the release of ANP, 2) examine the effects of resistance and endurance exercise on post exercise blood pressure and 3) evaluate the potential correlations of ANP release with any observed changes. Thirteen males (24.3±2.4yrs.) performed 15 min of unilateral leg press (65% 1 RM) and, one week later ~15 min (based on summed cardiac cycles of the resistance trial) of cycle ergometry (65% V0₂ ₚₑₐₖ). Blood pressure was measured using an intra-arterial catheter during exercise and for 1 h post exercise. Arterial blood was drawn at rest, 5, 10 and 15 min of exercise and 1 1/2, 3, 5, 10, 15, 30, 45 and 60 min post exercise for subsequent analysis of hematocrit and αANP. No differences occurred in blood pressure responses between trials, but significant decrements in blood pressure occurred post exercise compared to pre exercise. Systolic pressure was ~20mmHg lower from 10 min post exercise until measurements terminated at 60 min post exercise. Mean pressure was also significantly attenuated by ~7 mmHg from 30 min post exercise onwards. Only slight (non significant) elevations in αANP concentration were detected immediately following exercise with no elevation present by 5 min post exercise. It was concluded that post exercise hypotension occurs with acute bouts of either resistance or endurance exercise and that αANP does not appear to be directly related to this hypotensive effect. This study was supported by the Natural Sciences and Engineering Research Council of Canada