[Homologous and heterologous regulations of endothelin receptors on smooth muscle cells].
In vascular smooth muscle cells, the vasoconstrictor peptide, endothelin (ET-1) possesses specific binding sites sensitive to homologous and heterologous regulation. In this study, we have compared the regulation of ET-1 receptors induced by ET-1 and by angiotensin II. After 18 hours preincubation of cultured rat aortic smooth muscle cells at 37 degrees C in presence of vasoactive substances (1 microM) such as norepinephrine, Met- and Leu-enkephalins, bradykinin, serotonin, histamine or carbachol, the binding characteristics of [125I]ET-1 were not modified. On the same conditions, Arg-vasopressin (1 microM) was able to down-regulate ET-1 receptors by less than 30 p. 100 whereas both ET-1 (1 nM) and angiotensin II (10 nM) reduced the number of ET-1 binding sites (Bmax) by more than 50 p. 100 without modification of the affinity (Kd). The time course of the effect of the two peptides showed a rapid decrease of ET-1 binding sites induced by ET-1 and a comparatively slow regulation elicited by angiotensin II. Sar1-Ile8-angiotensin II blocked the effect of angiotensin II. These results show that ET-1 and angiotensin II can regulate ET-1 receptors and suggest a possible modulation of ET-1 activity by endogenous levels of the two peptides.
Roubert
P
P
Institut Henri-Beaufour, Les Ulis, France.
Gillard
V
V
Plas
P
P
Chabrier
P E
PE
Braquet
P
P
D000804:Angiotensin II / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D003470:Culture Media; D016232:Endothelins / Q000378:metabolism / Q000502:physiology*; D004730:Endothelium, Vascular / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017466:Receptors, Endothelin
D003470:Culture Media; D016232:Endothelins; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin; D000804:Angiotensin II
Régulations homologue et hétérologue des récepteurs de l'endothéline sur cellules musculaires lisses.