Reference : Interactions between calcium channels and SK channels in midbrain dopamine neurons an...
Scientific journals : Article
Human health sciences : Pharmacy, pharmacology & toxicology
http://hdl.handle.net/2268/201931
Interactions between calcium channels and SK channels in midbrain dopamine neurons and their impact on pacemaker regularity: Contrasting roles of N- and L-type channels.
English
de Vrind, V. []
Scuvée-Moreau, Jacqueline mailto [Université de Liège > Département des sciences biomédicales et précliniques > Pharmacologie >]
Drion, Guillaume mailto [Université de Liège > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Systèmes et modélisation >]
Hmaied, Cyrine mailto []
Philippart, Fabian mailto [Université de Liège > Département des sciences biomédicales et précliniques > Pharmacologie >]
Engel, Dominique mailto [Université de Liège > Département des sciences biomédicales et précliniques > Pharmacologie >]
Seutin, Vincent mailto [Université de Liège > Département des sciences biomédicales et précliniques > Pharmacologie >]
27-Jun-2016
European Journal of Pharmacology
Elsevier Science
788
274-279
Yes (verified by ORBi)
International
0014-2999
Amsterdam
The Netherlands
[en] Dopamine ; SK Channels ; Calcium ; Pacemaker ; Neurons
[en] Although small-conductance Ca2+-activated K+ (SK) channels and various types of voltage-gated Ca2+ (Cav) channels have been described in midbrain dopaminergic neurons, the nature of their interactions is unclear. More particularly, the role of various Cav channel types in either promoting irregularity of firing (by generating an inward current during SK channel blockade) or promoting regularity of firing (by providing the source of Ca2+ for the activation of SK channels) has not been systematically explored. We addressed this question using intracellular and extracellular recordings from substantia nigra, pars compacta (SNc), dopaminergic neurons in rat midbrain slices. Neurons were pharmacologically isolated from their differences. When examining the ability of various Cav channel blockers to inhibit the SK-mediated afterhyperpolarization (AHP), we found that only the N-type Cav channel blocker ω-conotoxin-GVIA was able to reduce the apamin-sensitive AHP, but only partially (~40%). Specific blockers of L, P/Q, T or R channels had no effect on this AHP. Combining ω-conotoxin-GVIA and other specific blockers did not yield greater block and even the broad Cav blocker Cd2+ induced a submaximal (~75%) effect. Extracellular recordings examining firing regularity yielded congruent results: none of the specific blockers was able to increase firing irregularity to the extent that the specific SK blocker apamin did. The irregularity of firing observed with apamin could only be reversed by blocking L-type Ca2+ channels. Thus various sources of Ca2+ appear to be required for SK channel activation in SNc neurons (some of them still unidentified), ensuring robustness of pacemaking regularity.
http://hdl.handle.net/2268/201931

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