Homologous desensitization of the effects of endothelin on rabbit aorta rings and on cultured rat aorta smooth muscle cells.
The effects of endothelin-1 on normal and everted rabbit aorta rings and on cultured rat aortic smooth muscle cells were studied. Endothelin-1 (40 nM) contracted both normal and everted rings, and was still able to induce a prolonged contraction in Ca2(+)-free medium. Treatment of cultured cells with 100 nM endothelin-1 caused a sharp transient increase in 45Ca2+ efflux. The contractile and 45Ca2+ responses showed severe and specific desensitization towards endothelin-1; the responses to angiotensin II and adrenaline were not affected. The contractile responses to endothelin-1 were not affected by previous treatment with angiotensin II or with the angiotensin receptor antagonist, [Sar1,Ala8]angiotensin II. It is concluded that endothelin-1 acts on its own specific receptors to elicit Ca2+ mobilization from both intracellular and extracellular sources.
Miasiro
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Department of Biophysics, Escola Paulista de Medicina, Sao Paulo, Brazil.
Paiva
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AC
D000804:Angiotensin II / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001011:Aorta; D002118:Calcium / Q000494:pharmacology*; D016232:Endothelins; D004730:Endothelium, Vascular / Q000187:drug effects*; D004837:Epinephrine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular; D010455:Peptides / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D014661:Vasoconstriction / Q000187:drug effects*
D016232:Endothelins; D010455:Peptides; D000804:Angiotensin II; D002118:Calcium; D004837:Epinephrine