Functional evidence for different endothelin receptors in the lung.
The present study was undertaken to compare and contrast the characteristics of the pulmonary and systemic vascular responses to endothelin (ET) isoforms in the intact spontaneously breathing cat under conditions of constant pulmonary blood flow and left atrial pressure. When pulmonary vasomotor tone (PVT) was actively increased by intralobar infusion of U-46619, intralobar arterial bolus injections of 1 microgram ET-1, 1 microgram ET-2, or 3 micrograms ET-3 markedly decreased lobar arterial pressure, systemic arterial pressure, and systemic vascular resistance. After seven repeated injections of ET-1 or ET-2 to separate groups of cats, pulmonary and systemic responses were largely reversed from vasodilation to vasoconstriction. In contrast, the pulmonary vasodilator response to ET-3 remained intact after multiple ET-3 injections, whereas its systemic vasodilator response was lost. Repeated intralobar arterial bolus injections of ET-1, ET-2, or ET-3 also caused the loss of pulmonary vasodilation to subsequent doses of ET-1, ET-2, or sarafotoxin 6b but not to ET-3. The present data suggest that the pulmonary and systemic vasodilator responses to ET-1 and ET-2 undergo tachyphylaxis and cross-tachyphylaxis. In contrast, the pulmonary vasodilator response to ET-3, unlike its systemic vasodilator response, is resistant to tachyphylaxis and cross-tachyphylaxis. The present data provide a functional correlate for the existence of at least two ET receptor subtypes, ETA-like and ETC-like receptors, in the adult pulmonary vascular bed.
Department of Internal Medicine, Louisiana State University Medical School, New Orleans.
H L
HL
Lippton
T A
TA
Hauth
G A
GA
Cohen
A L
AL
Hyman
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D002415:Cats; D019806:Cromakalim; D016232:Endothelins / Q000494:pharmacology; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D008168:Lung / Q000378:metabolism*; D008297:Male; D015221:Potassium Channels / Q000187:drug effects; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011652:Pulmonary Circulation / Q000187:drug effects / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D011758:Pyrroles / Q000494:pharmacology; D017466:Receptors, Endothelin / Q000378:metabolism*; D013618:Tachyphylaxis / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology; D014757:Viper Venoms / Q000494:pharmacology
D001578:Benzopyrans; D016232:Endothelins; D015221:Potassium Channels; D011450:Prostaglandin Endoperoxides, Synthetic; D011758:Pyrroles; D017466:Receptors, Endothelin; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; D019806:Cromakalim; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine; D001920:Bradykinin; D005905:Glyburide