title: Functional contributions of the plasma membrane calcium ATPase and the sodium-calcium exchanger at mouse parallel fibre to Purkinje neuron synapses.
abstract: We investigated how two calcium clearance mechanisms, the sodium-calcium exchanger-NCX, and the plasma membrane calcium ATPase-PMCA2, function at the facilitating cerebellar parallel fibre to Purkinje neuron (PF-PN) synapse. Forward mode NCX helped recover PF presynaptic calcium elevations when the PFs received a double stimulation and the calcium load was sufficiently high. A smaller presynaptic calcium load evoked by a single PF stimulation failed to recruit NCX in wild-type mice but did so when PMCA2 was absent in PFs from PMCA2 knockout mice. Simulated calcium dynamics using a simple single-compartment model reported qualitatively similar effects. Functionally, reduced NCX activity in the absence of PMCA also prolonged the recovery of facilitation at the PF-PN synapse, beyond that seen by reduced NCX activity alone. We conclude that PMCA and NCX work in parallel to accurately shape residual presynaptic calcium recovery dynamics and fine-tune facilitation at this important cerebellar synapse.
authors.affiliation: Department of Physiology, Brain Health Research Centre, University of Otago, Dunedin, New Zealand. ruth.empson@otago.ac.nz
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Roome
authors.forename: Thomas
authors.initials: T
authors.lastname: Knöpfel
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Empson
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D003198:Computer Simulation; D051379:Mice; D018345:Mice, Knockout; D009412:Nerve Fibers / Q000378:metabolism* / Q000502:physiology; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D011689:Purkinje Cells / Q000378:metabolism* / Q000502:physiology; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism* / Q000502:physiology; D009435:Synaptic Transmission
chemical_list: D019831:Sodium-Calcium Exchanger; D053499:Plasma Membrane Calcium-Transporting ATPases; C506959:Atp2b2 protein, mouse; D002118:Calcium