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Titolo:
Acetylcholine modulates respiratory pattern: Effects mediated by M3-like receptors in preBotzinger complex inspiratory neurons
Autore:
Shao, XM; Feldman, JL;
Indirizzi:
Univ Calif Los Angeles, Sch Med, Dept Neurobiol, Los Angeles, CA 90095 USAUniv Calif Los Angeles Los Angeles CA USA 90095 Los Angeles, CA 90095 USA
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 3, volume: 83, anno: 2000,
pagine: 1243 - 1252
SICI:
0022-3077(200003)83:3<1243:AMRPEM>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
PRE-BOTZINGER COMPLEX; LAYER-II NEURONS; BRAIN-STEM; POTASSIUM CONDUCTANCE; MUSCARINIC RECEPTORS; SYMPATHETIC NEURONS; CHOLINERGIC ACTION; PYRAMIDAL NEURONS; RHYTHM GENERATION; MEDULLARY SLICES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
74
Recensione:
Indirizzi per estratti:
Indirizzo: Shao, XM Univ Calif Los Angeles, Sch Med, Dept Neurobiol, Box 951763, Los Angeles, CA 90095 USA Univ Calif Los Angeles Box 951763 Los Angeles CA USA 90095 95 USA
Citazione:
X.M. Shao e J.L. Feldman, "Acetylcholine modulates respiratory pattern: Effects mediated by M3-like receptors in preBotzinger complex inspiratory neurons", J NEUROPHYS, 83(3), 2000, pp. 1243-1252

Abstract

Perturbations of cholinergic neurotransmission in the brain stem affect respiratory motor pattern both in vivo and in vitro; the underlying cellular mechanisms are unclear. Using a medullary slice preparation from neonatal rat that spontaneously generates respiratory rhythm, we patch-clamped inspiratory neurons in the preBotzinger complex (preBotC), the hypothesized site for respiratory rhythm generation, and simultaneously recorded respiratory-related motor output from the hypoglossal nerve (XIIn). Most (88%) of the inspiratory neurons tested responded to local application of acetylcholine (ACh) or carbachol (CCh) or bath application of muscarine. Bath application of 50 mu M muscarine increased the frequency, amplitude, and duration of XIIn inspiratory bursts. At the cellular level, muscarine induced a tonic inward current, increased the duration, and decreased the amplitude of the phasic inspiratory inward currents in preBotC inspiratory neurons recorded under voltage clamp at -60 mV. Muscarine also induced seizure-like activity evident during expiratory periods in XIIn activity; these effects were blocked by atropine. In the presence of tetrodotoxin (TTX), local ejection of 2 mM CCh or ACh onto preBotC inspiratory neurons induced an inward current along with an increase in membrane conductance under voltage clamp and induceda depolarization under current clamp. This response was blocked by atropine in a concentration-dependent manner. Bath application of 1 mu M pirenzepine, 10 mu M gallamine, or 10 mu M himbacine had little effect on the CCh-induced current, whereas 10 mu M 4-diphenylacetoxy-N-methylpiperidine methiodide blocked the current. The current-voltage (I-V) relationship of the CCh-induced response was linear in the range of -110 to -20 mV and reversed at -11.4 mV. Similar responses were found in both pacemaker and nonpacemaker inspiratory neurons. The response to CCh was unaffected when patch electrodes contained a high concentration of EGTA (11 mM) or bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (10 mM). The response to CCh was reduced greatly by substitution of 128 mM Tris-Cl for NaCl in the bath solution; the I-V curve shifted to the left and the reversal potential shifted to -47 mV. Lowering extracellular Cl- concentration from 140 to 70 mM had no effect on the reversal potential. These results suggest that in preBotC inspiratory neurons, ACh acts on M3-like ACh receptors on the postsynaptic neurons to open a channel permeable to Na+ and K+ that is not Ca2+ dependent. This inward cation current plays a major role in depolarizing preBotC inspiratory neurons,including pacemakers, that may account for the ACh-induced increase in thefrequency of respiratory motor output observed at the systems/behavioral level.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/09/20 alle ore 01:04:30