Postlethwaite, M. and Constanti, A. (2003) Evidence for the involvement of G-proteins in the generation of the slow poststimulus afterdepolarisation (sADP) induced by muscarinic receptor activation in rat olfactory cortical neurones in vitro. Brain Research, 978 (1-2). pp. 124-135. 10.1016/S0006-8993(03)02799-9.
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The involvement of G-proteins in generating the slow poststimulus afterdepolarising potential (sADP) induced by muscarinic receptor activation in immature (P10-20) rat olfactory cortical brain slice neurones was investigated under whole-cell patch clamp, using GTP-gamma-S (G-protein activator) or GDP-beta-S (G-protein blocker)-filled electrodes. In control experiments using K methylsulphate electrodes, cell resting potential (V(m)) and spike firing properties were unaffected over 10-15 min recording, although input resistance (R(N)) was slightly increased ( approximately 14%). Oxotremorine-M (OXO-M; 10 microM) produced a reversible slow depolarisation, an increase in R(N) ( approximately 90%) and induction of a slow poststimulus inward tail current (I(ADP)) (measured under voltage clamp at -60 mV) that was sustained during drug exposure (up to 15 min); the amplitude of slow inward rectifier (I(h)) currents activated from -50 mV were also apparently increased. By contrast, in GTP-gamma-S-loaded cells, R(N) was consistently decreased ( approximately 22%) and spike firing threshold (V(th)) was raised ( approximately 5 mV) after 10 min recording. In approximately 60% of loaded cells, a persistent muscarinic slow inward current and I(ADP) were induced by OXO-M; I(h) relaxation amplitude was also significantly decreased. The effects of GTP-gamma-S on R(N), V(th) and I(h) were partly counteracted by adding Ba(2+) (100 microM) to the bathing medium or mimicked by adding baclofen (GABA(B) receptor agonist; 100 microM) to normally-recorded cells. Intracellular GDP-beta-S (up to 30 min) had no effect on cell membrane properties or I(h), but irreversibly blocked the muscarinic slow inward current and I(ADP) induced by OXO-M. We conclude that both muscarinic responses require G-protein-linked transduction mechanisms for their generation.
|Uncontrolled Keywords:||Neurotransmitters, modulators, transporters and receptors, Acetylcholine receptors: muscarinic Whole-cell patch clamp; Brain slice; Rat olfactory cortex neurone; Muscarinic receptor; Slow afterdepolarising tail current (IADP); Slow h-current (Ih); G-proteins; GTP-γ-S, GDP-β-S|
|Departments, units and centres:||Department of Pharmacology > Department of Pharmacology|
|Journal or Publication Title:||Brain Research|
|Deposited By:||Library Staff|
|Deposited On:||24 Nov 2011 17:39|
|Last Modified:||24 Nov 2011 17:42|
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