Effect of amphiphiles on nitric oxide synthase in endothelial cells.
Amphiphiles are known to modulate the activity of ATPase, phospholipase A2, adenylate and guanylate cyclase amongst others and relax vascular smooth muscle. The effect of two amphiphiles, lysophosphatidylcholine (LPC) and digitonin on the activity of nitric oxide synthase (NOS), as measured by conversion of radiolabeled L-arginine to L-citrulline, has been studied. Neither digitonin (0.01 mmol/l) nor LPC (0.01 mmol/l) influenced NOS activity in endothelial cell homogenates. Digitonin but not LPC stimulated NOS in intact endothelial cells. NOS activity was markedly inhibited by L- but not by D-omega-nitroarginine (D-NNA, 0.1 mmol/l). L-NNA or D-NNA data demonstrate no effect of amphiphiles on isolated NOS. NOS activation may occur as a result of detergent action on the membrane.
Dudek
R
R
Department of Experimental Cardiology, Huntington Medical Research Institutes, Pasadena, Calif. 91101.
Conforto
A
A
Pinto
V
V
Bing
R J
RJ
D000594:Amino Acid Oxidoreductases / Q000187:drug effects*; D000818:Animals; D001011:Aorta; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002417:Cattle; D002474:Cell-Free System; D004072:Digitonin / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D019001:Nitric Oxide Synthase; D019335:Nitroarginine
D008244:Lysophosphatidylcholines; D019335:Nitroarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D004072:Digitonin