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Lack of importance of NO in β‐adrenoceptor‐mediated relaxation of large epicardial canine coronary arteries
Author(s) -
Béa MarieLuce,
Ghaleh Bijan,
Giudicelli JeanFrançois,
Berdeaux Alain
Publication year - 1994
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1994.tb14839.x
Subject(s) - coronary arteries , cardiology , medicine , carnivora , adrenergic receptor , receptor , artery
This study was designed to test the role of endothelium and the l ‐arginine/NO pathway in the relaxation of canine large coronary arteries to the β‐adrenoceptor agonist, isoprenaline. Relaxation of left circumflex (LCX) and left anterior descending (LAD) coronary arteries were measured in organ baths after contraction with the thromboxane analogue, U46619, either in absence or in presence of endothelium and in LCX arteries after pretreatment with N G ‐nitro‐ l ‐arginine‐methyl‐ester ( l ‐NAME). LAD arteries with and without endothelium relaxed identically to isoprenaline but their maximal relaxation was smaller than corresponding LCX arteries with endothelium. A slight but non significant difference was observed in LCX arteries with endothelium as compared to rings without endothelium or pretreated with l ‐NAME. No difference was observed in the relaxation of LCX arteries to forskolin in arteries with or without endothelium. These results suggest that endothelium is not essential and that NO is not directly involved in the relaxation of large coronary arteries induced by isoprenaline.