Tachyphylaxis to the vasopressor effects of endothelin in rat aortic rings.
Endothelin-1 (ET-1), a potent vasoconstrictor peptide released by endothelial cells, binds with high affinity to surface receptors and is highly resistant to dissociation. We observed tachyphylaxis to the pressor effects of a second application of ET-1 in rat aortic rings and investigated the mechanism of this effect. Developed tension increased progressively with doses of ET-1 ranging from 1 to 500 nM (P < 0.001), and tensions with rechallenge were correspondingly decreased (P < 0.001). In response to 500 nM ET-1, tension increased 1,599 +/- 72 (SE) mg/mg ring wt. Rechallenge with 500 nM ET-1 led to contraction of only 33 +/- 40 mg/mg ring wt. Tachyphylaxis was seen up to 6 h after initial challenge. Pretreatment with nicardipine, lidoflazine, nitroglycerin, and sphingosine did not affect tachyphylaxis. Pretreatment with 500 microM dansylcadaverine (an inhibitor of endothelin internalization) markedly inhibited ET-1-induced contraction and also inhibited tachyphylaxis to ET-1. Further studies with radiolabeled ET-1 suggested that subsequent ET-1 binding is markedly decreased after an initial ET-1 challenge. Dansylcadaverine inhibited ET-1 internalization and also inhibited the decreased binding seen with ET-1 rechallenge. Rat aortic rings demonstrate tachyphylaxis to the pressor effect of a second dose of ET-1. The mechanism appears to be related to binding and subsequent internalization of endothelin-receptor complexes. This effect suggests a possible mechanism for sustained decreases in systemic vascular resistance.
Hollenberg
S M
SM
Critical Care Medicine Department, National Institutes of Health, Bethesda, Maryland 20892.
Shelhamer
J H
JH
Cunnion
R E
RE
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D002103:Cadaverine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D013618:Tachyphylaxis; D014655:Vascular Resistance / Q000187:drug effects*
D016232:Endothelins; C008542:monodansylcadaverine; D002103:Cadaverine