AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 1 41-R48, Copyright © 1997 by American Physiological Society

ARTICLES

Endothelin-1 limits increases in blood flow to native and collateral-dependent myocardium

J. D. Symons, S. V. Rendig, L. W. Fu and J. C. Longhurst
Department of Internal Medicine, University of California-Davis 95616, USA.

We hypothesized that blood flow to collateralized and noncollateralized myocardium is improved by antagonism of endothelin (ET) A receptors. Coronary collateral development was stimulated by placing an ameroid constrictor around the left circumflex coronary artery (LCx; collateralized region) in 11 swine. After 35 +/- 2 days, the left anterior descending coronary artery (LAD; noncollateralized region) was autoperfused at constant pressure using blood from a femoral artery. In group 1 (n = 6) transmural blood flow was measured using radioactive microspheres in the LAD, LCx, and border regions (i.e., area between LAD and LCx) during pacing stress while vehicle (phosphate-buffered saline) was infused into the LAD coronary artery (pace 1). Approximately 55 min later, a second period of pacing (pace 2) was performed in the presence of ETA receptor antagonism (BQ-123; 5 mg.ml-1.min-1 ic). In the time control group (group 2, n = 5) vehicle was infused during both pacing periods. Indexes of myocardial oxygen demand were similar between paces 1 and 2 in each group. Compared with the first pacing period, transmural blood flow (ml.100 g-1.min-1) was higher (P < 0.05) during ETA receptor antagonism (i.e., pace 2) in the LAD (105 +/- 8 vs. 139 +/- 9), border (51 +/- 5 vs. 83 +/- 7), and LCx regions (22 +/- 3 vs. 41 +/- 4, respectively) in group 1. In group 2, while perfusion in the border (98 +/- 17 vs. 103 +/- 16) and LCx regions (19 +/- 4 vs. 27 +/- 6) was similar in paces 1 and 2, LAD transmural flow was greater (134 +/- 9 vs. 160 +/- 13; P < 0.05) during the second pacing period. However, the percent increase in LAD flow comparing pace 1 with 2 was greater (P < 0.05) in group 1 (39 +/- 6%) compared with group 2 (20 +/- 7%). These data suggest that during the stress of pacing blood flow to collateralized and noncollateralized myocardium is improved in the presence of ETA receptor blockade.

This article has been cited by other articles:

				J. D. Symons and S. Schaefer Na+/H+ exchange subtype 1 inhibition reduces endothelial dysfunction in vessels from stunned myocardium Am J Physiol Heart Circ Physiol, October 1, 2001; 281(4): H1575 - H1582. [Abstract] [Full Text] [PDF]

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