Human, Monkey and Dog Coronary Artery Responses to Serotonin and 5-Carboxamidotryptamine

Abstract

In beagle coronary arteries, serotonin-induced contractions are related directly to advancing age from 30 days to 12 years. This change is not associated with age-dependent endothelial disfunction. Contractile responses to serotonin of dog and monkey coronary arteries are evidently greater in the proximal portion than in the distal. Serotonin-induced contractions are in the order of human > monkey > dog arteries. On the other hand, 5-carboxamidotryptamine (5-CT), a 5-HT1 -like receptor agonist, relaxes dog coronary arteries, but contracts the human and monkey arteries. Relaxations of the dog arteries are dependent on endothelium, and are suppressed by methysergide but not altered by ketanserin. Human and monkey artery contractions by 5-CT and serotonin are not potentiated by endothelium denudation, and are attenuated by methysergide and ketanserin. It appears that endothelial serotonergic receptors do not contribute to relaxations in primate coronary arteries, whereas endothelial 5-HT1 -like receptor activation participates in the release of EDRF in dog coronary arteries. Contractions caused by 5-CT in human and monkey coronary arteries may be associated with predominant activation of 5-HT1-like receptor subtypes over 5-HT2 receptors, whereas those by serotonin are due mainly to 5-HT2 receptor activation.