Dissociation of the Renin-Angiotensin-Aldosterone System to Post-Exercise Hypotension

PURPOSE: Acute bouts of exercise <10-minutes have been shown to reduce resting blood pressure. Moreover, this transient reduction of blood pressure following an acute bout of exercise is more profound in individuals with essential or borderline hypertension and may continue for several hours post-exercise. Isolation of the cause of post-exercise hypotension (PEH) remains elusive. Hormones involved in natriuresis and diuresis could be implicated. This study examined the effect of an acute bout of dynamic exercise on several cardiovascular variables, and key metabolites in hypertensive men inspiring variant PO2.  
METHODS: Nine borderline hypertensive males not on medication, mean arterial pressure = 106 ± 5 mmHg, aged 50 ± 10 yr, (mean ± S.D.), were studied over three trials. The randomised double-blind trials were 30-minutes of cycle exercise at 60% of the normoxic VO2max inspiring 16% O2, (hypo) 50% O2 (hyper) and 20.93% O2 (normo). Peripheral venous blood was sampled pre-, post-, 1 -hour post- (P1), 2-hours post- (P2) and 7-hours post-exercise (P3). Venous concentrations were corrected for plasma volume shifts.
RESULTS: Following exercise PEH was elicited (P<0.05). The peripheral venous concentration of adrenaline (Ad) was elevated following exercise (P<0.05) from the P1 point until cessation of the study. Noradrenaline (Nad) and Angiotensin 2 (Ag2) concentrations did not change across the trial (P>0.05). Renin (Ren) concentration increased following exercise (P<0.05) but returned to baseline by P1. Aldosterone (Aldo) concentration increased following exercise (P<0.05) but returned to baseline by P2.
CONCLUSIONS: The results of the present study indicate that Ad, Nad, Ag2, Ren and Aldo secretion are unrelated to PEH. Furthermore, it appears that in the subjects investigated, the venous concentrations of Ad, Nad, Ag2, Ren and Aldo are critically dependent on the absolute work-load experienced.