NDLI: Purinergic and nitrergic junction potential in the human colon.

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Gallego, Diana Gil, Víctor Aleu, Jordi Aulí, Mariona Clavé, Pere Jiménez, Marcel
Description	Country affiliation: Spain Author Affiliation: Gallego D ( Department of Cell Biology, Physiology and Immunology, Edifici V, Universitat Autònoma de Barcelona 08193, Bellaterra, Barcelona, Spain.)
Abstract	The aim of the present work is to investigate a putative junction transmission [nitric oxide (NO) and ATP] in the human colon and to characterize the electrophysiological and mechanical responses that might explain different functions from both neurotransmitters. Muscle bath and microelectrode techniques were performed on human colonic circular muscle strips. The NO donor sodium nitroprusside (10 microM), but not the P2Y receptor agonist adenosine 5'-O-2-thiodiphosphate (10 microM), was able to cause a sustained relaxation. NG-nitro-L-arginine (L-NNA) (1 mM), a NO synthase inhibitor, but not 2'-deoxy-N6-methyl adenosine 3',5'-diphosphate tetraammonium salt (MRS 2179) (10 microM), a P2Y antagonist, increased spontaneous motility. Electrical field stimulation (EFS) at 1 Hz caused fast inhibitory junction potentials (fIJPs) and a relaxation sensitive to MRS 2179 (10 microM). EFS at higher frequencies (5 Hz) showed biphasic IJP with fast hyperpolarization sensitive to MRS 2179 followed by sustained hyperpolarization sensitive to L-NNA; both drugs were needed to fully block the EFS relaxation at 2 and 5 Hz. Two consecutive single pulses induced MRS 2179-sensitive fIJPs that showed a rundown. The rundown mechanism was not dependent on the degree of hyperpolarization and was present after incubation with L-NNA (1 mM), hexamethonium (100 microM), MRS 2179 (1 microM), and NF023 (10 microM). We concluded that single pulses elicit ATP release from enteric motor neurons that cause a fIJP and a transient relaxation that is difficult to maintain over time; also, NO is released at higher frequencies causing a sustained hyperpolarization and relaxation. These differences might be responsible for complementary mechanisms of relaxation being phasic (ATP) and tonic (NO).
File Format	HTM / HTML
ISSN	01931857
Issue Number	3
Volume Number	295
e-ISSN	15221547
Journal	AJP: Gastrointestinal and Liver Physiology
Language	English
Publisher	American Physiological Society
Publisher Date	2008-09-01
Publisher Place	United States
Access Restriction	Subscribed
Subject Keyword	Discipline Physiology Discipline Gastroenterology Adenosine Triphosphate Metabolism Colon, Sigmoid Innervation Enteric Nervous System Gastrointestinal Motility Muscle Relaxation Muscle, Smooth Nitrergic Neurons Nitric Oxide Action Potentials Aged Aged, 80 And Over Drug Effects Electric Stimulation Enzymology Enzyme Inhibitors Pharmacology Humans Middle Aged Neural Inhibition Neuromuscular Junction Nicotinic Antagonists Nitric Oxide Donors Nitric Oxide Synthase Antagonists & Inhibitors Receptors, Purinergic P2 Time Factors Journal Article Research Support, Non-u.s. Gov't
Content Type	Text
Resource Type	Article
Subject	Hepatology Physiology Physiology (medical) Gastroenterology

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