[Effects of ACh on the electric activity of rostral ventrolateral medullary neurons of rat in vitro].
Extracellular single-unit discharges were obtained from 165 spontaneously active neurons within the region of the rostral ventrolateral medulla (RVLM) by glass microelectrode from 89 brain slices of the Sprague-Dawley rats. The units could be divided into three types: regular (61.8%), irregular (24.2%) and silent (14%). Acetylcholine (ACh, 0.1, 0.3 mumol/L) showed four kinds of effects on spontaneous discharges of RVLM neurons: excitatory, inhibitory, biphasic and non-responsive, counting respectively 41.8%, 20%, 3% and 35.2% of the neurons tested. The excitatory effect of ACh was dose-dependent. The effects, either excitatory or inhibitory, of ACh (n = 49) were mostly blocked by atropine (0.3 mumol/L, n = 42). The excitatory effect of ACh (n = 14) could be blocked mainly by selective antagonist of M1 receptor, pirenzepine (PZ, 30 nmol/L, n = 9), but not by selective antagonist of M2 receptor, methoctramine (MT) and AFDX-116. The inhibitory effect of ACh (n = 10) could be blocked mostly by M2 receptor antagonist MT (30 nmol/L, n = 7); and this inhibitory effect (n = 9) could be blocked mostly by another M2 receptor antagonist AFDX-116 (30 nmol/L, n = 6), but not by M1 receptor antagonist PZ.
Chu
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XP
Department of Physiology, Shanghai Medical University.
Li
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Xu
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D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D003959:Diamines / Q000494:pharmacology; D004594:Electrophysiology; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D008839:Microelectrodes; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000502:physiology; D010890:Pirenzepine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D003959:Diamines; D018727:Muscarinic Antagonists; D010890:Pirenzepine; D000109:Acetylcholine; C054938:methoctramine