Atrial natriuretic peptide and urinary sodium balance during physical exercise.

Atrial natriuretic peptide (ANP), plasma renin activity (PRA), plasma aldosterone and urinary fractional excretion of sodium (%FENa) were measured in 22 athletes before and after 1 h running. After exercise the hormones increased significantly, while %FENa decreased. In fact, the percent PRA increases resulted higher than the percent ANP increases with a significant inverse correlation. It is concluded that hemodynamic changes during strenuous and prolonged physical exercise lead to the inhibition of the natriuretic properties of ANP by stimulating the renin-angiotensin-aldosterone system, although a feedback mechanism of modulation between ANP and PRA seems to occur.