Renin and hemodynamic responses to exercise in borderline hypertensives

In this study, we examined the relationship between baseline plasma renin (REN) and hemodynamic variables during recovery from aerobic exercise in 10 Caucasian (C) and 10 African-American (AA) borderline hypertensive females.

Subjects attended three preliminary sessions and an experimental session in which treadmill walking was performed for 40 minutes at a moderate intensity. During this session, blood was drawn at baseline prior to exercise and immediately following. Blood pressure and other hemodynamic variables were recorded at rest before exercise and for 2 hours afterwards. The average difference from baseline during the two hour recovery period was calculated for each variable and used as the dependent variable in a multiple regression analysis.

For mean arterial pressure and cardiac output, the regression slopes did not differ between AA and C. However, during recovery, the average difference from baseline for systemic vascular resistance (SVR) increased in AA but decreased in C.

In conclusion, REN had a significant effect on SVR but no effect on the other hemodynamic variables during recovery from aerobic exercise. It appears as if the peripheral vasculature in AA may be more sensitive than in C to the vasoconstrictive effects of the renin angiotensin system.