Endothelium-dependent inhibition of ergonovine-induced contraction is impaired in porcine coronary arteries with regenerated endothelium.
The inhibitory effects of the endothelium against ergonovine-induced contraction were examined in isolated porcine coronary arteries under normal conditions and after endothelial regeneration. Endothelium-dependent responses were examined in vitro in normal Yorkshire pigs (n = 16) and in pigs that had undergone balloon endothelium removal of the left anterior descending coronary artery (LAD) 4 weeks before the study (n = 10). The presence of a complete endothelial lining was confirmed histologically. In rings from normal arteries contracted with prostaglandin F2 alpha in the presence of indomethacin and ketanserin (a 5-HT2-serotonergic blocker), ergonovine caused endothelium-dependent relaxations. They were attenuated by rauwolscine (an alpha 2-adrenergic blocker), inhibited by methiothepin (a combined 5-HT1- and 5-HT2-serotonergic blocker) or by pertussis toxin (an inhibitor of several G proteins) and abolished by oxyhemoglobin (a selective inactivator of endothelium-derived relaxing factor). In quiescent rings from normal arteries, ergonovine caused contractions that were inhibited by the presence of the endothelium; this endothelium-dependent inhibition was abolished by oxyhemoglobin. The direct contractions were not affected by prazosin (an alpha 1-adrenergic blocker), rauwolscine, 6-hydroxydopamine (an agent causing chemical sympathetectomy), or diphenhydramine (an H1-histaminergic blocker) but were inhibited by ketanserin. In rings with regenerated endothelium contracted with prostaglandin F2 alpha, the endothelium-dependent relaxations to ergonovine were reduced significantly and were not inhibited by pertussis toxin. In quiescent rings with regenerated endothelium, the endothelium-dependent inhibition of ergonovine-induced contraction was less.(ABSTRACT TRUNCATED AT 250 WORDS)
Shimokawa
H
H
Department of Physiology and Biophysics, Mayo Clinic, Rochester, MN 55905.
Flavahan
N A
NA
Shepherd
J T
JT
Vanhoutte
P M
PM
D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D004874:Ergonovine / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009924:Organ Culture Techniques; D012038:Regeneration / Q000187:drug effects*; D013552:Swine
D004874:Ergonovine