title: Role of the nitric oxide/cyclic GMP pathway and ascorbic acid in 3-morpholinosydnonimine (SIN-1)-induced increases in dopamine secretion from PC12 cells. A microdialysis in vitro study.
abstract: We showed previously, using in vitro microdialysis, that activation of the nitric oxide (NO)/cyclic GMP pathway was the underlying mechanism of exogenous NO-induced dopamine (DA) secretion from PC12 cells. In this study, infusion of the potential peroxynitrite generator 3-morpholinosydnonimine (SIN-1, 1.0 mM for 60 min) induced a long-lasting decrease in dialysate DA+3-methoxytyramine (3-MT) in dialysates from PC12 cell suspensions. Ascorbic acid (0.2 mM) co-infusion allowed SIN-1 to increase dialysate DA+3-MT. SIN-1+ascorbic acid effects were abolished by Ca(2+) omission. Infusion of high K(+) (75 mM) induced a 2.5-fold increase in dialysate DA+3-MT. The increase was inhibited by SIN-1 co-infusion. Conversely, co-infusion of ascorbic acid (0.2 mM) with SIN-1+high K(+) resulted in a 3.5 fold increase in dialysate DA+3-MT. The L-type Ca(2+) channel inhibitor nifedipine selectively inhibited the DA+3-MT increase pertaining to high K(+), while the soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]-oxadiazolo[4,3]quinoxalin-1-one selectively inhibited the increase pertaining to SIN-1 effects. These results suggest that activation of the NO/sGC/cyclic GMP pathway is the underlying mechanism of extracellular Ca(2+)-dependent effects of SIN-1 on DA secretion from PC12 cells. Extracellular Ca(2+) entry occurs through nifedipine-insensitive channels. Ascorbic acid is a key determinant in modulating the distinct profiles of SIN-1 effects.
authors.affiliation: Department of Pharmacology, University of Sassari, viale S. Pietro 43B, 07100 Sassari, Italy.
authors.forename: Pier Andrea
authors.initials: PA
authors.lastname: Serra
authors.forename: Rossana
authors.initials: R
authors.lastname: Migheli
authors.forename: Gaia
authors.initials: G
authors.lastname: Rocchitta
authors.forename: Maria G
authors.initials: MG
authors.lastname: Taras
authors.forename: Maria P
authors.initials: MP
authors.lastname: Mura
authors.forename: Maria R
authors.initials: MR
authors.lastname: Delogu
authors.forename: Giovanni
authors.initials: G
authors.lastname: Esposito
authors.forename: Maria S
authors.initials: MS
authors.lastname: Desole
authors.forename: Egidio
authors.initials: E
authors.lastname: Miele
authors.forename: Maddalena
authors.initials: M
authors.lastname: Miele
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D006152:Cyclic GMP / Q000037:antagonists & inhibitors / Q000378:metabolism; D003956:Dialysis / Q000379:methods; D004298:Dopamine / Q000031:analogs & derivatives* / Q000378:metabolism*; D004347:Drug Interactions; D066298:In Vitro Techniques; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D009543:Nifedipine / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D010069:Oxadiazoles / Q000494:pharmacology; D016716:PC12 Cells; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors
chemical_list: C116907:1H-(1,2,4)oxadiazolo(4,3-a)-quiloxalin-1-one; D000975:Antioxidants; D002121:Calcium Channel Blockers; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine; D006152:Cyclic GMP; D009543:Nifedipine; C001746:3-methoxytyramine; D001205:Ascorbic Acid; D011188:Potassium; D002118:Calcium; D004298:Dopamine