Date of Defense

6-13-1996

Department

Biological Sciences

First Advisor

Craig Hartman, Biological Sciences

Second Advisor

Lenoard Beuving, Biological Sciences

Third Advisor

Cindy Hoorn, Biological Sciences

Abstract

The purpose of this study was to investigate the relationship of apoptosis and necrosis in ischemic as compared to ischemic/reperfused myocardial tissue. Reversible ischemia was produced in a marginal branch of the left coronary artery of anesthetized, open-chested rabbits with the aid of an adjustable prolene ligature. Ischemia of 30 min or 150 min with no reperfusion and ischemia of 30 min with 120 min of reperfusion (I/R) was produced. After sacrifice, the hearts were removed and treated with a solution of triphenyl tetrazolium chloride (TTC) to detect necrotic tissue. Samples across the transmural border of the left ventricle were then taken such that normal tissue (non-ischemic) and central ischemic tissue were both sampled. Sections were cut from each sample such that tissue was divided evenly across the transmural border into five arbitrary zones from the subepicardium to the subendocardium. Samples were then stained for apoptotic activity by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling and nuclear staining with diaminobenzidine. Apoptotic to necrotic activity was compared both in the ischemic only to the I/R regions of tissue and across the myocardium from the most epicardial to the most endocardial zones employing computer-assisted imaging analysis. Apoptotic nuclear staining was found to be significantly higher in the I/R myocardium (535±155 nuclei/mm2) than in both groups having ischemia only (10±5 nuclei/mm2, pooled value). Necrotic tissue in the 30 min and 120 min ischemic groups was found to be 37% and 63% of that measured in the I/R treatment group. The results of the study suggest that the necrotic tissue death from myocardial ischemia and reperfusion is associated with an increased apoptotic activity under these conditions.

Comments

Research assistance provided by Theron M. Wall and Carol A. Simmons of Pharmacia & Upjohn.

Access Setting

Honors Thesis-Campus Only

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