Abrupt withdrawal of chronic nitroglycerin treatment may predispose the coronary circulation to spasm. To test this hypothesis directly, we developed a technique for performing selective coronary arteriography in the intact rabbit with images obtained by video-based methods or cineangiographic film. Experiments were then conducted in rabbits treated three times daily with topical nitroglycerin ointment for 6 weeks and in age- and sex-matched control animals. Forty hours after cessation of treatment, animals were anesthetized, and ECG and coronary vasoactive effects (determined by coronary arteriography) of ergonovine, 0.2 mg/kg (intravenous) and indomethacin, 25 mg/kg (intravenous) were assessed. Of six nitroglycerin-treated rabbits, one died of ventricular fibrillation prior to arteriographic study. The remaining five developed ECG abnormalities (single ventricular premature beats, nonsustained ventricular tachycardia, and ST segment deviation) upon challenge with ergonovine or indomethacin. Neither agent evoked ECG changes in control rabbits. In contrast, the degree of luminal diameter reduction in epicardial coronary arteries provoked by ergonovine or indomethacin did not differ between control and nitroglycerin-treated animals. Focal coronary artery spasm was not observed in any rabbit. Our results demonstrate that selective coronary arteriography in rabbits is feasible and that changes in vessel caliber may be assessed from images thus obtained. Data from this study indicate that ergonovine- and indomethacin-induced ECG abnormalities observed in nitroglycerin-treated rabbits cannot be ascribed to epicardial coronary artery spasm.
|Number of pages||7|
|Journal||American Heart Journal|
|State||Published - Aug 1987|
Bibliographical noteFunding Information:
From the University of Kentucky, College of Pharmacy, Division Pharmacology and Toxicology and College of Medicine, Division Cardiovascular Medicine, Lexington, Kentucky 40536-0053 Supported in part by grant from the American Heart Association, Kentucky Affiliate. Received for pub&&ion June 9, 1986; accepted Jan. 20, 1987. Reprint requests: Mark N. Gillespie, Ph.D., University of Kentucky, College of Pharmacy, Lexington, KY 40536.0083.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine