Diverse Relaxation Responses of Canine Large and Small Conductive Coronary Arteries to Glyceryl Trinitrate and Nitric Oxide on the One Hand and to 8-Bromoguanosine 3′:5′ Cyclic Monophosphate on the Other

Abstract

Glyceryl trinitrate (GTN) and nitric oxide (NO) preferentially relaxed the large (2 mm in diameter) conductive coronary artery (CCA) of the dog, while 8-bromoguanosine 3′:5′ cyclic monophosphate preferentially relaxed the small one (0.6 mm in diameter). Nither L-cysteine nor L-acetylcysteine affected GTN-induced relaxation in small- and large-CCA. These results indicate that not different biotransformation of GTN to NO, but a process or processes operative between activation of guanylate cyclase and that of cyclic GMP-dependent protein kinase seems to be responsible for the preferential dilatation of large-CCA.