A physiologically-evoked M1-muscarinic depolarization in guinea-pig inferior mesenteric ganglion neurons
| Autor: | D.L. Kreulen, Todd L. Anthony |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Atropine
Male medicine.medical_specialty Inferior mesenteric ganglion Physiology Colon Guinea Pigs Action Potentials Hexamethonium Compounds Distension Neurotransmission Biology Hexamethonium Hexamethonium compound chemistry.chemical_compound Internal medicine medicine Animals Ganglia Sympathetic General Neuroscience Depolarization Pirenzepine Receptors Muscarinic Endocrinology chemistry Anesthesia Excitatory postsynaptic potential Carbachol Female Neurology (clinical) Stress Mechanical Gastrointestinal Motility Mechanoreceptors medicine.drug |
| Zdroj: | Journal of the autonomic nervous system. 46(3) |
| ISSN: | 0165-1838 |
| Popis: | The possibility of physiologically-evoked muscarinic excitatory synaptic potentials was examined in the inferior mesenteric ganglion (IMG) with intracellular microelectrodes in vitro. Three types of depolarizing responses were evoked concurrently by colonic distension: (1) fast nicotinic excitatory postsynaptic potentials (EPSPs); (2) an 'intermediate' time course depolarization and (3) a long time course potential that persisted throughout the period of distension. After hexamethonium was superfused over the ganglia the long time course potential was observed in 91% of IMG neurons. Intermediate time course of depolarizations were observed in 100% of IMG neurons and correlated with each propulsive contraction of the distal colon. The intermediate depolarizations had an average amplitude of 1.8 +/- 0.1 mV (n = 175 individual events; 27 preparations) with an average duration of 11.9 +/- 0.8 sec (n = 28 individual events). The intermediate time course synaptic potentials were accompanied by an increase in input resistance of 15% (n = 6). Superfusion of atropine (1 microM; n = 6) on the IMG or the M1-selective antagonist pirenzepine (1 microM; n = 5) abolished the intermediate time course synaptic potentials during distension. Superfusion of the M2-selective antagonist AF-DX 116 (1 microM; n = 4) had no effect. In all preparations examined, distension-induced intermediate time course depolarizations were blocked by tetrodotoxin (TTX) (3 microM). Pressure ejection of carbachol (1 mM, 60-100 ms pulses) evoked depolarizations of similar amplitude (6.5 +/- 0.7 mV; n = 18) and duration to the intermediate depolarizations observed during propulsive contractions.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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