Angiotensin II and phorbol-esters potently down-regulate endothelin (ET-1) binding sites in vascular smooth muscle cells.
[125I]ET-1 binding to vascular smooth muscle cells showed an apparent single class of high affinity recognition sites with a Kd of 2.12 +/- 0.46 nM and a Bmax of 81.2 +/- 5.2 fmol/10(6) cells. The specific binding was equally and totally displaced by ET-1 and ET-2 whereas ET-3 presented a different pattern. We investigated heterologous regulation of ET-1 binding sites by preincubating the cells with angiotensin II (AII), Arg-vasopressin, bradykinin, enkephalins, serotonin, norepinephrine and carbachol, for 18 h at 37 degrees C. Only AII pretreatment resulted in an important and dose-dependent decrease of ET-1 binding capacity. Sar1-Ile8-AII inhibited the regulatory effect of AII. Furthermore, preexposure of the cells with phorbol-12,13 dibutyrate but not with phorbol-12,13 didecanoate also resulted in a concentration-dependent diminution of ET-1 binding sites. These findings suggest that AII may selectively down-regulate ET-1 binding sites in vascular smooth muscle cells by a mechanism involving protein kinase C.
Roubert
P
P
Institut Henri Beaufour Les Ulis, France.
Gillard
V
V
Plas
P
P
Guillon
J M
JM
Chabrier
P E
PE
Braquet
P
P
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects*; D016232:Endothelins; D004730:Endothelium, Vascular / Q000502:physiology; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D017466:Receptors, Endothelin
D016232:Endothelins; D010455:Peptides; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin; D000804:Angiotensin II; D015240:Phorbol 12,13-Dibutyrate