title: Nitric oxide inhibition of NaCl secretion in the opercular epithelium of seawater-acclimated killifish, Fundulus heteroclitus.
abstract: Nitric oxide (NO) modulates epithelial ion transport pathways in mammals, but this remains largely unexamined in fish. We explored the involvement of NO in controlling NaCl secretion by the opercular epithelium of seawater killifish using an Ussing chamber approach. Pharmacological agents were used to explore the mechanism(s) triggering NO action. A modified Biotin-switch technique was used to investigate S-nitrosation of proteins. Stimulation of endogenous NO production via the nitric oxide synthase (NOS) substrate l-arginine (2.0 mmol l-1), and addition of exogenous NO via the NO donor SNAP (10-6to 10-4mol l-1), decreased the epithelial short-circuit current (Isc). Inhibition of endogenous NO production by the NOS inhibitor l-NAME (10-4mol l-1) increased Iscand revealed a tonic control of ion transport by NO in unstimulated opercular epithelia. The NO scavenger PTIO (10-5mol l-1) supressed the NO-mediated decrease in Isc, and confirmed that the effect observed was elicited by release of NO. The effect of SNAP on Iscwas abolished by inhibitors of the soluble guanylyl cyclase (sGC), ODQ (10-6mol l-1) and Methylene Blue (10-4mol l-1), revealing NO signalling via the sGC/cGMP pathway. Incubation of opercular epithelium and gill tissues with SNAP (10-4mol l-1) led to S-nitrosation of proteins, including Na+/K+-ATPase. Blocking of NOS with l-NAME (10-6mol l-1) or scavenging of NO with PTIO during hypotonic shock suggested an involvement of NO in the hypotonic-mediated decrease in IscYohimbine (10-4mol l-1), an inhibitor of α2-adrenoceptors, did not block NO effects, suggesting that NO is not involved in the α-adrenergic control of NaCl secretion.
authors: Department of Biology, University of Southern Denmark, Odense M DK-5230, Denmark luciegerber@biology.sdu.dk.
authors: Lucie
authors: 0000-0003-3837-4879
authors: L
authors: Gerber
authors: Department of Biology, University of Southern Denmark, Odense M DK-5230, Denmark.
authors: Frank B
authors: FB
authors: Jensen
authors: Department of Biology, University of Southern Denmark, Odense M DK-5230, Denmark.
authors: Steffen S
authors: SS
authors: Madsen
authors: Department of Biology, St Francis Xavier University, Antigonish, NS, Canada B2G 2W5.
authors: William S
authors: WS
authors: Marshall
mesh_terms: D000064:Acclimatization / Q000187:drug effects / Q000502:physiology*; D000322:Adrenergic Agonists / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D015153:Blotting, Western; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D023781:Fundulidae / Q000502:physiology*; D006162:Guanylate Cyclase / Q000378:metabolism; D007038:Hypotonic Solutions / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D015538:Nitrosation; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D012623:Seawater; D015398:Signal Transduction / Q000187:drug effects; D012965:Sodium Chloride / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D012995:Solubility
chemical_list: D000322:Adrenergic Agonists; D004791:Enzyme Inhibitors; D007038:Hypotonic Solutions; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D012965:Sodium Chloride; D026423:S-Nitroso-N-Acetylpenicillamine; D001120:Arginine; D019001:Nitric Oxide Synthase; D006162:Guanylate Cyclase; D000254:Sodium-Potassium-Exchanging ATPase; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester
keywords: Cl− secretion; Epithelial ion transport; Mummichog; NO; sGC/cGMP pathway