title: Sphingosine 1-phosphate inhibits nitric oxide production induced by interleukin-1beta in rat vascular smooth muscle cells.
abstract: Sphingosine 1-phosphate (S1P) is a lipid mediator that exerts potent and diverse biological effects on several cardiovascular cells. We investigated the effect of S1P on interleukin (IL)-1beta-induced nitric oxide (NO) production and inducible NO synthase (iNOS) expression in rat vascular smooth muscle cells (VSMCs). S1P inhibited NO production at concentrations higher than 0.1 muM; this was associated with the inhibition of iNOS protein and mRNA expression. S1P also inhibited IL-1beta-induced GTP cyclohydrolase I (GTPCH) mRNA expression. Pertussis toxin (PTX) partially attenuated the inhibitory effects of S1P on NO production and iNOS protein induction, whereas it completely blocked the inhibitory effects on iNOS and GTPCH mRNA expression. S1P inhibited iNOS expression in Ca(2+)-depleted conditions; PTX did not modify this effect. The Rho kinase inhibitor Y 27632 partially but significantly attenuated the inhibitory effect of S1P on iNOS expression in Ca(2+)-depleted condition but did not affect it in the presence of Ca(2+). S1P significantly inhibited IL-1beta-induced persistent activation of extracellular signal-regulated kinase (ERK) but had no effect in Ca(2+)-depleted conditions. Thus, S1P inhibits IL-1beta induction of NO production and iNOS expression in rat VSMCs through multiple mechanisms involving both PTX-sensitive and -insensitive G proteins coupled to S1P receptors. Furthermore, Ca(2+)-dependent ERK inhibition and Ca(2+)-independent Rho kinase activation might be involved in the inhibitory mechanism of iNOS expression. Through its action on NO production by VSMCs, S1P may play an important role in the progression of local vascular injury associated with thrombosis, atherosclerosis, and hypertension.
authors.affiliation: Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Machida
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Hamaya
authors.forename: Sachiko
authors.initials: S
authors.lastname: Izumi
authors.forename: Yumika
authors.initials: Y
authors.lastname: Hamaya
authors.forename: Kenji
authors.initials: K
authors.lastname: Iizuka
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Igarashi
authors.forename: Masaru
authors.initials: M
authors.lastname: Minami
authors.forename: Roberto
authors.initials: R
authors.lastname: Levi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hirafuji
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D053583:Interleukin-1beta / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D053583:Interleukin-1beta; D008246:Lysophospholipids; D012333:RNA, Messenger; C060506:sphingosine 1-phosphate; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D013110:Sphingosine; D002118:Calcium