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Under non-exercise conditions, atrial natriuretic peptide (ANP) elevation suppresses plasma renin activity (PRA) and aldosterone (PA). A similar effect of ANP on PRA-PA during exercise has been suggested but not demonstrated. We measured ANP, PRA, PA, plasma potassium (K ), and changes in plasma volume (PV) and blood volume (BV) at rest and during incremental cycle ergometer exercise to exhaustion in ten healthy males. Plasma concentrations (X /- SE) of hormones and electrolytes increased (P < 0.05) during exercise: ANP (68 /- 14 to 207 /- 48 pg[middle dot]ml-1), PA (11.2 /- 2.2 to 18.8 /- 3.4 ng[middle dot]dl-1), PRA (5.1 /- 1.1 to 8.2 /- 1.6 ng[middle dot]ml-1 -90 min-1), and K (4.2 /- 0.1 to 5.5 /- 0.1 mEq). PV and BV declined, reaching maximal deflections from baseline during the 100% stage (12.9 /- 1.5 and 8.4 /- 0.8% decreases, respectively). There were positive correlations between ANP and PRA (r = 0.58; P < 0.01), ANP and PA (r = 0.56; P < 0.01), and PRA and PA (r = 0.80; P < 0.001). Increases in K did not correlate with increases in PA. The fall in PV correlated with elevations in PRA (r = -0.67; P < 0.01) and PA (r = -0.58; P < 0.01), and the fall in BV correlated with elevations in PRA (r = -0.62; P < 0.01) and PA (r = -0.44; P < 0.02). ANP production was related to exercise intensity (gauged by heart rate response; r = 0.58; P < 0.01). In conclusion, vigorous exercise induces increases in ANP, PRA, and PA, with no ANP suppression of the PRA-PA axis noted, although suppression could be masked by the complex interplay of various stimulators of PRA and PA during exercise. These systems appear to be responding to independent stimuli: ANP to increases in venous return, with consequent atrial distention and increases in heart rate; PRA-PA to decreases in PV and BV, decreases in renal perfusion pressure, and increases in sympathetic activity.

(C)1990The American College of Sports Medicine