In:
Journal of Neurophysiology, American Physiological Society, Vol. 100, No. 5 ( 2008-11), p. 2684-2701
Abstract:
Large diameter cells in rat deep cerebellar nuclei (DCN) can be distinguished according to the generation of a transient or weak rebound burst and the expression of T-type Ca 2+ channel isoforms. We studied the ionic basis for the distinction in burst phenotypes in rat DCN cells in vitro. Following a hyperpolarization, transient burst cells generated a high-frequency spike burst of ≤450 Hz, whereas weak burst cells generated a lower-frequency increase ( 〈 140 Hz). Both cell types expressed a low voltage–activated (LVA) Ca 2+ current near threshold for rebound burst discharge (−50 mV) that was consistent with T-type Ca 2+ current, but on average 7 times more current was recorded in transient burst cells. The number and frequency of spikes in rebound bursts was tightly correlated with the peak Ca 2+ current at −50 mV, showing a direct relationship between the availability of LVA Ca 2+ current and spike output. Transient burst cells exhibited a larger spike depolarizing afterpotential that was insensitive to blockers of voltage-gated Na + or Ca 2+ channels. In comparison, weak burst cells exhibited larger afterhyperpolarizations (AHPs) that reduced cell excitability and rebound spike output. The sensitivity of AHPs to Ca 2+ channel blockers suggests that both LVA and high voltage–activated (HVA) Ca 2+ channels trigger AHPs in weak burst compared with only HVA Ca 2+ channels in transient burst cells. The two burst phenotypes in rat DCN cells thus derive in part from a difference in the availability of LVA Ca 2+ current following a hyperpolarization and a differential activation of AHPs that establish distinct levels of membrane excitability.
Type of Medium:
Online Resource
ISSN:
0022-3077
,
1522-1598
DOI:
10.1152/jn.90427.2008
RVK:
XA 10000 ; XA 552555
Language:
English
Publisher:
American Physiological Society
Publication Date:
2008
detail.hit.zdb_id:
80161-6
detail.hit.zdb_id:
1467889-5
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