Effect of physical exercise in hypobaric conditions on atrial natriuretic peptide secretion.

Abstract

To evaluate the role of atrial natriuretic peptide (ANP) in exercise-related cardiovascular and hormonal adjustments in hypobaric conditions, 14 young athletes performed a maximal ergometer test in a hypobaric chamber adjusted to simulate the altitudes of sea level and 3,000 m. Plasma immunoreactive ANP levels rose from 5.89 to 35.1 pmol/l at sea level and rose significantly less (P less than 0.05), from 5.36 to 22.3 pmol/l, at simulated 3,000 m. Plasma immunoreactive amino-terminal peptide of proANP (NT-proANP) levels increased to the same extent at sea level and at simulated 3,000 m (from 240 to 481 pmol/l and from 257 to 539 pmol/l, respectively). Plasma immunoreactive aldosterone increased significantly less at simulated 3,000 m (P less than 0.05), but the changes in plasma renin were similar in both conditions. Plasma immunoreactive endothelin-1 and serum erythropoietin levels remained unchanged. In conclusion, we found a blunted ANP response to maximal exercise of ANP in acute hypobaric exposure compared with that in normobaric conditions, but no significant difference in the NT-proANP responses between the two conditions. The divergence may be due to stimulation of the elimination mechanism of ANP.