Atrial natriuretic factor inhibits Ca(2+)-dependent K+ fluxes in cultured vascular smooth muscle cells.
The interaction of the synthetic fragment Arg101-Tyr126 of atrial natriuretic factor (ANF) with Ca(2+)-dependent K+ efflux was studied in the following six different cell models: cultured vascular smooth muscle cells from rat aorta; isolated rat glomeruli; human platelets; cultured endothelial cells from bovine aorta; peritoneal mouse macrophages; human red cells. In human red cells and mouse macrophages, the dose-response curves of K+ efflux as a function of Ca2+ ionophore, A23187, concentration were not modified by addition of ANF. In endothelial cells and platelets, ANF slightly inhibited Ca(2+)-dependent K+ efflux. In renal glomeruli, ANF inhibits about one-third of this flux and in vascular smooth muscle cells ANF induced a five- to tenfold increase in the EC50 of A23187 effect. In experiments performed at constant concentrations of A23187, the IC50 of ANF was approximately 10(-9) mol/l. Similar results were obtained in mouse macrophages with cyclic GMP (cGMP). Our results suggest that ANF is able to counterbalance an increase in cytosolic free Ca2+ content in vascular smooth muscle and some glomerular cells. This effect may result from the ability of this hormone to stimulate cGMP synthesis.
Garay
R
R
Inserm U7/CNRS LA 318, Hôpital Necker, Paris, France.
Hannaert
P
P
Rodrigue
F
F
Dunham
B
B
Marche
P
P
Genest
J
J
Braquet
P
P
Bianchi
C
C
Cantin
M
M
Meyer
P
P
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D051381:Rats
D000001:Calcimycin; D009320:Atrial Natriuretic Factor; D011188:Potassium; D002118:Calcium