title: Nitric oxide responses of air-breathing and water-breathing fish.
abstract: Nitric oxide (NO), exogenously administered or endogenously produced by NO synthase (NOS), is an important regulator of lung ventilation and perfusion in mammals. This study attempts to investigate the evolutionary history of this system in fish and its possible relationship to air breathing. The gas bladder of Hoplerythrinus unitaeniatus (air-breathing teleost) and Oncorhynchus mykiss (non-air-breathing teleost) and the lung of Lepidosiren paradoxa (air-breathing dipnoan) all exhibited elevated guanosine 3',5'-cyclic monophosphate (cGMP) levels in response to 1 microM sodium nitroprusside. Only the H. unitaeniatus gas bladder responded to 10 microM acetylcholine chloride (ACh) with increased cGMP levels. The ACh response was inhibited by N omega-nitro-L-arginine methyl ester, which inhibits NOS. These data suggest that although tissues from each species may respond to exogenous NO, only the gas bladder of H. unitaeniatus appears to synthesize NO through NOS. This is the first report of constitutive NOS outside of the central nervous system in a teleost. These results also imply that NOS did not necessarily coevolve with air breathing in fish.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, Canada.
authors.forename: J F
authors.initials: JF
authors.lastname: Staples
authors.forename: W M
authors.initials: WM
authors.lastname: Zapol
authors.forename: K D
authors.initials: KD
authors.lastname: Bloch
authors.forename: N
authors.initials: N
authors.lastname: Kawai
authors.forename: V M
authors.initials: VM
authors.lastname: Val
authors.forename: P W
authors.initials: PW
authors.lastname: Hochachka
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000388:Air; D000400:Air Sacs / Q000187:drug effects / Q000378:metabolism; D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D005075:Biological Evolution; D006152:Cyclic GMP / Q000378:metabolism; D005399:Fishes / Q000502:physiology*; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase; D009599:Nitroprusside / Q000494:pharmacology; D017686:Oncorhynchus mykiss / Q000502:physiology*; D012119:Respiration / Q000502:physiology*; D013045:Species Specificity; D014867:Water
chemical_list: D014867:Water; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D006152:Cyclic GMP; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester