title: Effects of melatonin on pulmonary and coronary vessels are exerted through perivascular nerves.
abstract: The effects of melatonin on porcine pulmonary and coronary vessels have been studied. Vessels were isolated from normal pigs, placed in a tissue bath, and precontracted with 30 mM KCl. The biophysical responses to cumulative doses of melatonin were then assessed. In the pulmonary artery, melatonin caused a dose-dependent relaxation which was blocked by vasoactive intestinal peptide antagonists or prior 6-hydroxydopamine treatment of the vessels. In the coronary artery, melatonin caused the reverse, a dose-dependent contraction which was blocked by the alpha antagonist prazosin or prior 6-hydroxydopamine treatment. These experiments indicate that melatonin has different mechanisms of action in the coronary and pulmonary circulation, although both seem to depend on the integrity of perivascular 6-hydroxydopamine sensitive nerves. Such differing mechanisms may provide insight into pathophysiological events in the lungs (such as nocturnal asthma) and heart (early morning coronary infarction).
authors.affiliation: College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg 24060.
authors.forename: L B
authors.initials: LB
authors.lastname: Weekley
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000294:innervation; D005260:Female; D066298:In Vitro Techniques; D008550:Melatonin / Q000494:pharmacology*; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D016627:Oxidopamine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects* / Q000294:innervation; D013373:Substance P / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013552:Swine; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D011189:Potassium Chloride; D016627:Oxidopamine; D008550:Melatonin