title: Nitric oxide and nitrosocysteine mimic nonadrenergic, noncholinergic hyperpolarization in canine proximal colon.
abstract: Previous evidence suggests that nonadrenergic, noncholinergic (NANC) inhibitory neurotransmission in visceral muscles may be mediated by nitric oxide (NO). We have demonstrated that NO and the NO carrier S-nitrosocysteine can mimic the hyperpolarization in colonic muscle caused by nerve stimulation. The finding that S-nitrosocysteine breaks down fast enough to cause inhibitory junction potential (IJP)-like hyperpolarizations suggests that NO could be stored as a nitrosothiol in secretory vesicles in nerve terminals. Oxyhemoglobin blocked hyperpolarization responses to NO and S-nitrosocysteine and NANC IJPs. These findings suggest that NO is a biologically active transmitter substance in NANC inhibitory neurotransmission. NO enhanced the open probability of Ca(2+)-activated K+ channels in isolated colonic muscle cells. These channels may mediate the hyperpolarization response to NANC neurotransmission in colonic muscles.
authors.affiliation: Department of Physiology, University of Nevada, School of Medicine, Reno 89557.
authors.forename: K D
authors.initials: KD
authors.lastname: Thornbury
authors.forename: S M
authors.initials: SM
authors.lastname: Ward
authors.forename: H H
authors.initials: HH
authors.lastname: Dalziel
authors.forename: A
authors.initials: A
authors.lastname: Carl
authors.forename: D P
authors.initials: DP
authors.lastname: Westfall
authors.forename: K M
authors.initials: KM
authors.lastname: Sanders
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D003106:Colon / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D010108:Oxyhemoglobins / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D026403:S-Nitrosothiols; D013237:Stereoisomerism; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D010108:Oxyhemoglobins; D015221:Potassium Channels; D026403:S-Nitrosothiols; D009569:Nitric Oxide; C021315:S-nitrosocysteine; D003545:Cysteine; D002118:Calcium