title: Relaxin up-regulates inducible nitric oxide synthase expression and nitric oxide generation in rat coronary endothelial cells.
abstract: Relaxin (RLX) is a reproductive hormone with vasodilatatory properties on several organs, including the heart. RLX-induced vasodilatation appears to depend on the stimulation of endogenous NO production. Here, we investigate whether RLX acts on rat coronary endothelial (RCE) cells in vitro by inducing changes of NO generation and, if so, to clarify the possible mechanism of action. RCE cells were treated for 24 h with vehicle (controls) or RLX, alone or in association with inhibitors of NO synthesis or dexamethasone, which inhibits transcription of NO synthase gene. In some experiments, inactivated RLX was given in the place of authentic RLX. Expression of NO synthase isozymes II and III was analyzed by immunocytochemistry, Western blot, and RT-PCR. NO production was evaluated by the Griess reaction for nitrite and the NO-sensitive fluorophore DAF-2/DA. Agonist-induced changes of intracellular Ca2+ transient were studied with the Ca2+-sensitive fluorophore Fura 2-AM. RLX was found to up regulate NOS II mRNA and protein and to stimulate intrinsic NO generation, likely through the activation of a dexamethasone-sensitive transcription factor, and to decrease agonist-induced intracellular Ca2+ transient. Conversely, RLX had negligible effects on NOS III expression. By these biological effects, RLX may afford significant protection against cardiovascular disease.
authors.affiliation: Department of Preclinical and Clinical Pharmacology, University of Florence, Florence, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Failli
authors.forename: Silvia
authors.initials: S
authors.lastname: Nistri
authors.forename: Silvia
authors.initials: S
authors.lastname: Quattrone
authors.forename: Luca
authors.initials: L
authors.lastname: Mazzetti
authors.forename: Mario
authors.initials: M
authors.lastname: Bigazzi
authors.forename: Tatiana Bani
authors.initials: TB
authors.lastname: Sacchi
authors.forename: Daniele
authors.initials: D
authors.lastname: Bani
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012065:Relaxin / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D009569:Nitric Oxide; D012065:Relaxin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D002118:Calcium