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This Article Full Text Full Text (PDF) All Versions of this Article: 288/6/H2684    most recent 01047.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (13) Citing Articles via Google Scholar Google Scholar Articles by Dedkov, E. I. Articles by Tomanek, R. J. Search for Related Content PubMed PubMed Citation Articles by Dedkov, E. I. Articles by Tomanek, R. J.

Reduction of heart rate by chronic ₁-adrenoceptor blockade promotes growth of arterioles and preserves coronary perfusion reserve in postinfarcted heart

Departments of ¹Anatomy and Cell Biology and ²Internal Medicine and ³The Cardiovascular Center, University of Iowa Carver College of Medicine, and ⁴Department of Veterans Affairs Medical Center, Iowa City, Iowa

Submitted 10 October 2004 ; accepted in final form 26 January 2005

Adequate growth of coronary vasculature in the remaining left ventricular (LV) myocardium after myocardial infarction (post-MI) is a crucial factor for myocyte survival and performance. We previously demonstrated that post-MI coronary angiogenesis can be stimulated by bradycardia induced with the ATP-sensitive K⁺ channel antagonist alinidine. In this study, we tested the hypothesis that heart rate reduction with -blockade may also induce coronary growth in the post-MI heart. Transmural MI was induced in 12-mo-old male Sprague-Dawley rats by occlusion of the left anterior descending coronary artery. Bradycardia was induced by administration of the -adrenoceptor blocker atenolol (AT) via drinking water (30 mg/day). Three groups of rats were compared: 1) control/sham (C/SH), 2) MI, and 3) MI + AT. In the MI + AT rats, heart rate was consistently reduced by 25–28% compared with C/SH rats. At 4 wk after left anterior descending coronary ligation, infarct size was similar in MI and MI + AT rats (67.1 and 61.5%, respectively), whereas a greater ventricular hypertrophy occurred in bradycardic rats, as indicated by a higher ventricular weight-to-body weight ratio (3.4 ± 0.1 vs. 2.8 ± 0.1 mg/g in MI rats). Analysis of LV function revealed a smaller drop in ejection fraction in the MI + AT than in the MI group (24 vs. 35%). Furthermore, in MI + AT rats, maximal coronary conductance and coronary perfusion reserve were significantly improved compared with the MI group. The better myocardial perfusion indexes in MI + AT rats were associated with a greater increase in arteriolar length density than in the MI group. Thus chronic reduction of heart rate induced with -selective blockade promotes growth of coronary arterioles and, thereby, facilitates regional myocardial perfusion in post-MI hearts.

myocardial infarction; angiogenesis; coronary circulation; resistance vessels; capillaries

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