Faculty Collaboration Database

Endothelium-dependent contraction and relaxation of the human and canine internal mammary artery: studies on bypass graft vasospasm. Surgery 1991 Aug;110(2):127-34; discussion 135

Date

08/01/1991

Pubmed ID

1858024

Scopus ID

2-s2.0-0026337738 (requires institutional sign-in at Scopus site)   31 Citations

Abstract

The internal mammary artery (IMA) is the preferred conduit for coronary artery bypass graft because of superior late patency. However, IMA vasospasm may contribute to myocardial ischemia and early postoperative morbidity. To investigate mechanisms of vasospasm, we compared the reactivity of human and canine IMA segments in vitro to agonists known to release endothelium-derived contracting factor and endothelium-derived relaxing factor. Rings (4 mm in length) of human and canine IMA were studied in organ chambers. Human and canine vascular smooth muscle exhibited comparable contraction to norepinephrine (maximum = 7.55 +/- 0.63 gm and 6.4 +/- 0.90 gm, respectively) and relaxation to sodium nitroprusside. Human and canine IMAs exhibited comparable endothelium-derived relaxing factor-mediated relaxations to acetylcholine (human) and methacholine (canine). Human and canine IMA also exhibited comparable endothelium-dependent contraction to hypoxia (to 173.3% +/- 8.1% and 178.9% +/- 16.0% of initial prehypoxic tension; means +/- SEM; n = 12). Endothelium-dependent contraction to hypoxia in human and canine IMA could be attenuated by NG-monomethyl-L-arginine (10(-6) mol/L), a competitive inhibitor of L-arginine metabolism (n = 9 and n = 10 for human and canine; p less than 0.05). These studies establish that the canine is an appropriate model for study of human IMA vascular reactivity and that hypoxia can induce the release of an L-arginine-dependent, endothelium-derived contracting factor in the human and canine IMA. In vivo, the release of endothelium-derived contracting factor in response to hypoxemia may be cause of IMA vasospasm.

Author List

Lin PJ, Pearson PJ, Schaff HV

Author

Paul Joseph Pearson MD, PhD Chief, Professor in the Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acetylcholine
Animals
Arginine
Dogs
Endothelins
Female
Humans
Hypoxia
In Vitro Techniques
Male
Mammary Arteries
Methacholine Chloride
Muscle Contraction
Muscle Relaxation
Muscle, Smooth, Vascular
Nitric Oxide
Nitroprusside
Norepinephrine
omega-N-Methylarginine