Muscarinic receptor activation induces a prolonged post-stimulus afterdepolarization with a conductance decrease in guinea-pig olfactory cortex neurones in vitro.

Constanti, A. and Bagetta, G. (1991) Muscarinic receptor activation induces a prolonged post-stimulus afterdepolarization with a conductance decrease in guinea-pig olfactory cortex neurones in vitro. Neuroscience Letters, 131 (1). pp. 27-32. 10.1016/0304-3940(91)90329-R.

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DOI: 10.1016/0304-3940(91)90329-R

Abstract

The persistent excitation of guinea-pig olfactory cortical neurones in vitro by the muscarinic agonist oxotremorine-M (OXO-M) was investigated. In OXO-M (10-20 microM), a slowly-decaying afterdepolarization (sADP) accompanied by sustained repetitive firing was induced following a long depolarizing stimulus. The corresponding slow inward current (IADP) revealed under voltage clamp behaved like a K(+)-mediated tail current, but was associated with a decreased membrane conductance. IADP was insensitive to tetrodotoxin (TTX), Ba2+, Cs+, or 4-aminopyridine (4-AP), but was blocked by 500 microM TEA or TBA (tetrabutylammonium). The OXO-M response and IADP were also reduced by Cd2+ or Ca(2+)-free solution, suggesting a dependence on Ca(2+)-entry. We propose that OXO-M induces a novel outward K+ current that can be slowly de-activated by Ca(2+)-entry during a depolarizing stimulus. Summation of IADP tail currents could contribute to the sustained muscarinic excitation of mammalian cortical neurones.

Item Type:Article
Uncontrolled Keywords:Oxotremorine-M; Guinea-pig olfactory cortex; Muscarinic receptor; Slow afterdepolarization; Intracellular recording
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:2530
Journal or Publication Title:Neuroscience Letters
Deposited By:Library Staff
Deposited On:25 Nov 2011 09:54
Last Modified:25 Nov 2011 09:54

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