title: Protein kinase C masks nitric oxide synthase activity in vascular smooth muscle under basal conditions.
abstract: Under basal conditions there is no observable nitric oxide synthase (NOS) activity in vascular smooth muscle (VSM). Pretreatment of endothelium-denuded aortic rings from Sprague-Dawley rats with 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), (0.1 micromol/L) significantly attenuated phenylephrine (PE)-induced contractile responses in a dose-dependent manner. In the presence of 10 micromol/L Nomega-nitro-L-arginine (L-NNA) or 0.1 mmol/L aminoguanidine (AG), the inhibition of contractions at 10 nmol/L PE by H-7 was blocked by 88% or 52%, respectively. The blockade by antagonists was completely reversed by l-arginine but not by d-arginine, and alone they did not significantly alter PE-induced contraction of endothelium-denuded aorta. Methylene blue (MB, 50 micromol/L) also inhibited the action of H-7. The inhibitory effect of H-7 occurred after 5 minutes and was reversible. PE-induced contraction was also inhibited by the selective protein kinase C inhibitors calphostin C (10 micromol/L), and bisindolylmaleimide IV (Bis-IV, 10 micromol/L), but not by the selective protein kinase A inhibitor H-89 (0.1 micromol/L). These results indicate protein kinase C inhibits NOS activity in VSM under basal conditions. Incubation of tissues with either H-7 or calphostin C stimulates NO production, and immunocytochemical studies reveal the presence of NOS in VSM under basal conditions.
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Loren W
authors.initials: LW
authors.lastname: Kline
authors.forename: Junzhi
authors.initials: J
authors.lastname: Ji
authors.forename: Guei-Jane
authors.initials: GJ
authors.lastname: Wang
authors.forename: Sharla K
authors.initials: SK
authors.lastname: Sutherland
authors.forename: Peter K T
authors.initials: PK
authors.lastname: Pang
authors.forename: Christina G
authors.initials: CG
authors.lastname: Benishin
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D019335:Nitroarginine / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D019335:Nitroarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D011493:Protein Kinase C