title: Modulation of neuroeffector transmission in the guinea pig pulmonary artery by endogenous nitric oxide.
abstract: The influence of endogenous nitric oxide (NO) on neuroeffector transmission in segments of guinea pig pulmonary artery was analyzed by application of NG-monomethyl-L-arginine (L-NMMA). L-NMMA enhanced contractile responses to nerve stimulation and this enhancement was counteracted by L-arginine. The enhancement remained after removal of the endothelium. L-NMMA enhanced contractions to exogenous noradrenaline. After blockade of adrenergic transmission by phentolamine, L-NMMA enhanced contractions induced by nonadrenergic-noncholinergic (NANC) neurotransmission. Stimulation-induced release of [3H]noradrenaline was unchanged by L-NMMA. The results suggest that endogenous NO exerts a postjunctional inhibition on adrenergic neurotransmission in the guinea pig pulmonary artery. A concomitant pre- and/or postjunctional inhibition of NANC transmission is implicated. The neuromodulation by NO does not require an intact endothelium.
authors.affiliation: Department of Physiology, Karolinska Hospital, Karolinska Institutet, Stockholm, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Cederqvist
authors.forename: N P
authors.initials: NP
authors.lastname: Wiklund
authors.forename: M G
authors.initials: MG
authors.lastname: Persson
authors.forename: L E
authors.initials: LE
authors.lastname: Gustafsson
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009451:Neuroeffector Junction / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D011651:Pulmonary Artery / Q000294:innervation* / Q000378:metabolism; D009435:Synaptic Transmission; D014661:Vasoconstriction; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D009638:Norepinephrine