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J Thorac Cardiovasc Surg 1994;107:647-0647
© 1994 Mosby, Inc.

Letters to the Editor

Reactivity of gastroepiploic and internal mammary arteries

Erasme Hospital

808, Route de Lennik
B-1070 Brussels, Belgium

Jeanine Fontaine, PhD

Institut de Pharmacie
Université Libre de Bruxelles
Boulevard du Triomphe
B-1050 Brussels, Belgium

To the Editor:

We read with interest the article by Dignan and colleagues ¹ in the January 1992 issue of the JOURNAL, reporting that gastroepiploic artery (GEA) segments had a stronger contraction in response to potassium chloride, norepinephrine, and serotonin than did the internal mammary artery (IMA). They suggested that prevention of platelet-, adrenergic-, or potassium-induced contraction may be more important for GEA as an alternate coronary bypass conduit. To assess the role of the endothelium and to evaluate the response to endothelin-1, we also conducted a study on the GEA and IMA. ² The vessels were obtained from 11 patients undergoing gastrectomy or duodenopancreatectomy and from 16 patients during coronary artery bypass operations. The rings were suspended in organ chambers to record isometric tension. The experiments were performed in the presence of phentolamine (1 µmol/L), propranolol (1 µmol/L), and indomethacin (10 µmol/L). The relaxations in response to acetylcholine on vessels precontracted with prostaglandin F₂ were similar in both vessels. The maximal contractions to serotonin, normalized as a percent of potassium chloride–induced contraction (90 mmol/L) were 46% ± 15% for IMA and 18% ± 5% for GEA. Endothelium removal equally potentiated the responses to serotonin in both preparations. The maximal contractions to endothelin-1 were also higher in the IMA: 166% ± 19% versus 102% ± 6% of potassium chloride (p < 0.05) but were not affected by endothelium removal. However, the capacity to contract, expressed in tension developed, was higher in the GEA: the potassium chloride–induced (90 mmol/L) contraction was 2.6 ± 0.3 g in the IMA versus 7.9 ± 0.9 g in the GEA (p < 0.001). A histologic examination of the vessels tested showed similar wall thickness and paucity of atherosclerosis, but the media was mainly elastic in the IMA and muscular in the GEA, consistent with the results reported by Van Son and associates. ³

Our results thus extend those of Dignan and colleagues ¹; namely, a greater responsiveness of IMA, not only to potassium chloride and serotonin (when normalized as a percent of potassium chloride–induced contraction) but also to endothelin-1, a potent endogenous vasoconstrictor, and nevertheless a greater contractile capacity of GEA, which may be a disadvantage in terms of graft patency despite similar endothelial function.

References

1. Dignan RJ, Yeh T Jr, Dyke CM, et al. Reactivity of gastroepiploic and internal mammary arteries: relevance to coronary artery bypass grafting. J THORAC CARDIOVASC SURG 1992;103:116-23.[Abstract]
   
2. Unger P, Berkenboom G, Depierreux JM, Fontaine J. Influence of the endothelium on the responses to endogenous agonists in human internal mammary and gastroepiploic arteries [Abstract]. J Vasc Res 1992;29:216-7.
   
3. Van Son JAM, Smedts F, Vincent JG, van Lier HJJ, Kubat K. Comparative anatomic studies of various arterial conduits for myocardial revascularization. J THORAC CARDIOVASC SURG 1990;99:703-7.[Abstract]
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Jean-Marie De Smet Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Unger, P. Articles by Fontaine, J. Search for Related Content PubMed PubMed Citation Articles by Unger, P. Articles by Fontaine, J.