Nitric oxide: mediator of NANC hyperpolarization of opossum esophageal smooth muscle.
Activation of intrinsic nonadrenergic noncholinergic (NANC) esophageal nerves during peristalsis or by electrical field stimulation (EFS) in vitro produces a hyperpolarization followed by a depolarization of the circular smooth muscle of the opossum esophagus. N omega-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase, and nitric oxide (NO) were used to test the hypothesis that NO or a NO-containing compound is a mediator of this NANC nerve-induced hyperpolarization of circular esophageal smooth muscle. The transmembrane potential difference of esophageal circular smooth muscle cells was recorded with glass microelectrodes. Nerve-mediated membrane responses were evoked by single electrical pulses of 0.5 ms duration and 50 V amplitude. L-NNA abolished the initial hyperpolarization and reduced the amplitude of and the time to maximal depolarization. L-Arginine (1 mM), the substrate for NO synthase, antagonized the effect of L-NNA. Exogenous NO produced hyperpolarization of the smooth muscle membrane potential and attenuated the amplitudes of EFS-induced hyperpolarization and depolarization. The effect of NO was blocked neither by L-NNA nor by tetrodotoxin (1 microM). The data support the hypothesis that NO or a NO-containing compound mediates NANC nerve-induced responses of the esophageal smooth muscle membrane.
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C
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Department of Internal Medicine, University of Iowa College of Medicine, Iowa City.
Murray
J
J
Bates
J N
JN
Conklin
J L
JL
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D004947:Esophagus / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D005260:Female; D008297:Male; D008564:Membrane Potentials; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase; D019335:Nitroarginine; D009893:Opossums
D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases