Superiority of endothelin-1 over norepinephrine in exercise-induced alterations of the conduit artery tone of the non-exercised arm in patients with chronic heart failure

This study is aimed at examining the relative importance of norepinephrine and endothelin-1 in treadmill exercise-induced changes in brachial arterial tone of the non-exercised arm in patients with chronic heart failure (CHF) . Brachial artery diameter and blood flow were measured before and after ex ercise in eight healthy volunteers and 18 patients with stable chronic hear t failure by high-resolution ultrasound. Maximal exercise resulted in brach ial artery dilatation in controls (4.42+/-0.39 vs. 4.77+/-0.39 mm; P < 0.00 01) in contrast to constriction seen in the patients (5.27+/-0.67 vs. 5.12/-0.66 mm; P = 0.07). Both groups demonstrated a significant increase in bl ood flow after exercise. The pre-exercise (2.83+/-0.76 vs. 1.69+/-0.15 pmol /l; P = 0.0004), post-exercise (4.15+/-1.5 vs. 2.02+/-0.34 pmol/l; P = 0.00 04) and the percent increase (47.15+/-32.5 vs. 19.0+/-10.5%; P = 0.02) in e ndothelin-1 levels were significantly greater in patients than in controls. In contrast to endothelin-1, the exercise-induced percent increase in nore pinephrine was greater in controls than patients (100.7+/-51.8 vs. 49.8+/-4 3.4%; P = 0.01), The percent change in the diameter of the brachial artery in response to maximal exercise was significantly correlated to pre- (r = 0 .634; P = 0.003) and post-exercise (r = 0.467; P = 0.05) endothelin-l level s in patients but not in controls [pre-exercise (r = 0.07; P = 0.86), post- exercise (r = 0.310; P = 0.47)]. The change in the diameter of the brachial artery did not correlate with pre- or post-exercise plasma norepinephrine levels in either group, These findings suggest that endothelin-1 is potenti ally more important than norepinephrine in contributing exercise-induced br achial artery constriction in patients with chronic heart failure. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.