Renin-Angiotensin System Genes and Exercise Training-Induced Changes in Sodium Excretion in African American Hypertensives

Abstract

Objective: To determine whether angiotensinconverting enzyme (ACE) and angiotensinogen (AGT) genotypes could predict changes in urinary sodium excretion in response to short-term aerobic exercise training (AEX). Design: Longitudinal intervention. Setting: The study was conducted at the University of Maryland at College Park and at Baltimore, and the University of Pittsburgh General Clinical Research Center. Participants: 31 (age 53 6 2 years) sedentary, hypertensive (146 6 2/88 6 2 mm Hg) African Americans. Intervention: Aerobic exercise training (AEX) consisted of seven or eight consecutive days, 50 minutes per day, at 65% of heart rate reserve. Participants underwent a 24-hour period of ambulatory blood pressure (BP) monitoring and urine collection at baseline and 14–18 hours after the last exercise session. Main Outcome Measures: Angiotensiongen (AGT) M235T and ACE I/D genotype and sodium excretion and ambulatory BP. Results: Average sodium excretion for the entire group independent of genotype increased after AEX (108 6 9 vs 143 6 12 mEq/day, P5.003). Sodium excretion significantly increased after exercise training in the ACE II (114 6 22 vs 169 6 39 mEq/day, P5.04), but not in the ID (100 6 8 vs 133 6 17 mEq/day, P5.12) or DD (113 6 18 vs 138 6 11 mEq/day, P5.13) genotype groups. In the II genotype group, the increase in sodium excretion was significantly and inversely correlated with decreases in 24-hour diastolic (r52.88, P5.02) and mean (r52.95, P5.004) BP. The AGT TT and MT+MM genotype groups similarly increased their sodium excretion by 34 6 16 (P5.05) and 37 6 17 (P5.05) mEq/day respectively. Conclusions: These results suggest that African American hypertensives with the ACE II genotype may be more susceptible to sodium balance and BP changes with exercise training compared with those with the ID and DD genotypes.