Down-regulation of endothelin binding sites in rat vascular smooth muscle cells.
In cultured rat aortic smooth muscle cells, [125I]endothelin (ET-1) bound to an apparent single class of high affinity recognition sites with a dissociation constant of 1.84 +/- 0.29 nmol/L and a maximum binding of 62 +/- 10.5 fmol/10(6) cells. The binding was not affected by calcium antagonists or vasoactive substances, including angiotensin II, arginine vasopressin, atrial natriuretic factor and bradykinin. Exposure of the cells to ET-1 (0.01 nmol/L to 10 nmol/L) resulted in an apparent dose-dependent reduction of the number of endothelin binding sites with no significant modification of its binding affinity. The time course of the down-regulation of ET-1 binding sites showed that this effect was present after 30 min incubation and persisted after 18 h. This indicates that down-regulation of ET-1 binding sites can modulate the activity of ET-1 and suggests a rapid internalization of ET-1 in vascular cells.
Roubert
P
P
Institut Henri Beaufour, Les Ulis, France.
Gillard
V
V
Plas
P
P
Chabrier
P E
PE
Braquet
P
P
D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation / Q000502:physiology*; D016232:Endothelins; D007457:Iodine Radioisotopes; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000502:physiology*; D017466:Receptors, Endothelin
D016232:Endothelins; D007457:Iodine Radioisotopes; D010455:Peptides; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin