Juan Carlos Robles1, Cristine L Heaps. 1. Department of Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA.
Abstract
OBJECTIVE: To the test the hypothesis that exercise training would increase endothelin-mediated vasoconstriction in collateral-dependent arteries via enhanced contribution of ET(A). METHODS: An ameroid constrictor was surgically placed around the proximal LCX artery to induce gradual occlusion in Yucatan miniature swine. Eight weeks postoperatively, pigs were randomized into sedentary or exercise-training (treadmill; 5 days/week; 14 weeks) groups. Subsequently, arteries (~150 μm diameter) were isolated from collateral-dependent and nonoccluded myocardial regions and studied. RESULTS: Following exercise training, ET-1-mediated contraction was significantly enhanced in collateral-dependent arteries. Exercise training induced a disproportionate increase in the ET(A) contribution to the ET-1 contractile response in collateral-dependent arteries, with negligible contributions by ET(B). In collateral-dependent arteries of sedentary pigs, inhibition of ET(A) or ET(B) did not significantly alter ET-1 contractile responses in collateral-dependent arteries, suggesting compensation by the functionally active receptor. These adaptations occurred without significant changes in ET(A), ET(B), or ECE mRNA levels but with significant exercise-training-induced elevations in endothelin levels in both nonoccluded and collateral-dependent myocardial regions. CONCLUSIONS: Taken together, these data reveal differential adaptive responses in collateral-dependent arteries based upon physical activity level. ET(A) and ET(B) appear to compensate for one another to maintain contraction in sedentary pigs, whereas exercise-training favors enhanced contribution of ET(A).
OBJECTIVE: To the test the hypothesis that exercise training would increase endothelin-mediated vasoconstriction in collateral-dependent arteries via enhanced contribution of ET(A). METHODS: An ameroid constrictor was surgically placed around the proximal LCX artery to induce gradual occlusion in Yucatan miniature swine. Eight weeks postoperatively, pigs were randomized into sedentary or exercise-training (treadmill; 5 days/week; 14 weeks) groups. Subsequently, arteries (~150 μm diameter) were isolated from collateral-dependent and nonoccluded myocardial regions and studied. RESULTS: Following exercise training, ET-1-mediated contraction was significantly enhanced in collateral-dependent arteries. Exercise training induced a disproportionate increase in the ET(A) contribution to the ET-1 contractile response in collateral-dependent arteries, with negligible contributions by ET(B). In collateral-dependent arteries of sedentary pigs, inhibition of ET(A) or ET(B) did not significantly alter ET-1 contractile responses in collateral-dependent arteries, suggesting compensation by the functionally active receptor. These adaptations occurred without significant changes in ET(A), ET(B), or ECE mRNA levels but with significant exercise-training-induced elevations in endothelin levels in both nonoccluded and collateral-dependent myocardial regions. CONCLUSIONS: Taken together, these data reveal differential adaptive responses in collateral-dependent arteries based upon physical activity level. ET(A) and ET(B) appear to compensate for one another to maintain contraction in sedentary pigs, whereas exercise-training favors enhanced contribution of ET(A).
Authors: Thomas F Lüscher; Frank Enseleit; Richard Pacher; Veselin Mitrovic; Matthias R Schulze; Roland Willenbrock; Rainer Dietz; Valentin Rousson; David Hürlimann; Sebastian Philipp; Thomas Notter; Georg Noll; Frank Ruschitzka Journal: Circulation Date: 2002-11-19 Impact factor: 29.690
Authors: Christopher M O'Connor; Wendy A Gattis; Kirkwood F Adams; Vic Hasselblad; Bleakley Chandler; Aline Frey; Isaac Kobrin; Maurizio Rainisio; Monica R Shah; John Teerlink; Mihai Gheorghiade Journal: J Am Coll Cardiol Date: 2003-05-07 Impact factor: 24.094