title: ATP closes a potassium and opens a cationic conductance through different receptors in neurons of guinea pig submucous plexus.
abstract: Intracellular recordings were made to study the actions of ATP and related nucleotides on neurons from the guinea pig submucous plexus. Local application of ATP, by pressure, induced a depolarization in most AH-type neurons, which had a latency of several milliseconds, lasted for about 5 sec, appeared to reverse at about +4 mV and occurred concomitantly with a reduction in input resistance. Pressure application of ATP also depolarized the S-type neurons. In most of these cells the depolarization had two phases: the first component resembled the depolarization observed in AH cells and the second component was much slower in onset and was longer lasting (30-90 sec). The slower component was associated with an increase in input resistance, reversed polarity near the potassium equilibrium potential and was observed in isolation in 30% of S neurons. Superfusion of ATP or other analogs (0.03-10 microns) induced a slow depolarization in most of S neurons with the following rank order of potency: 2-methylthio-ATP > ATP > adenosine-5'-o-3-thiotriphosphate = ADP; alpha, beta-methylene ATP and beta, gamma-methylene ATP were inactive (10-100 microM). When whole-cell recordings were used, fast superfusion with ATP or other analogs (3-1000 microM) evoked, at negative membrane potentials, a rapidly desensitizing inward current. This current reversed polarity at about 0 mV and was much reduced in low extracellular sodium concentration. The rank order of potency of the used agonists was: ATP = adenosine-5'-o-3-thiotriphosphate = 2-methylthio-ATP > > alpha,beta-methylene ATP = beta,gamma-methylene ATP; adenosine, AMP or ADP (1 mM) were inactive.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Vollum Institute L-474, Oregon Health Sciences University, Portland.
authors.forename: C
authors.initials: C
authors.lastname: Barajas-López
authors.forename: R
authors.initials: R
authors.lastname: Espinosa-Luna
authors.forename: V
authors.initials: V
authors.lastname: Gerzanich
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D011983:Receptors, Purinergic / Q000378:metabolism; D013368:Submucous Plexus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D007473:Ion Channels; D015221:Potassium Channels; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate