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Hyperpolarization‐activated currents in presynaptic terminals of mouse cerebellar basket cells
Author(s) -
Southan Andrew P.,
Morris Neil P.,
Stephens Gary J.,
Robertson Brian
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.t01-1-00091.x
Subject(s) - hyperpolarization (physics) , inhibitory postsynaptic potential , neuroscience , patch clamp , membrane potential , gating , chemistry , cerebellum , biophysics , hcn channel , current clamp , electrophysiology , neuromodulation , ion channel , biology , biochemistry , central nervous system , stereochemistry , receptor , nuclear magnetic resonance spectroscopy
1 Using patch‐clamp techniques, a hyperpolarization‐activated current ( I h ) was recorded from synaptic terminals of mouse cerebellar basket cells. 2 Ih was blocked quickly and reversibly by 2 mM Cs + , and subtraction revealed a rapidly activating and deactivating I h current. Similar gating and block of presynaptic I h were also seen with the more selective inhibitor ZD 7288 (10 μM). 3 The time constant of activation (τ a ) of presynaptic I h current became faster with membrane hyperpolarization, being ≈74 ms at ‐130 mV, changing e‐fold for a 33 mV change in membrane potential. 4 Whole‐cell recordings from basket cell somata also revealed an I h current, which was similarly sensitive to block by ZD 7288. 5 Inhibition of I h by 10 μM ZD 7288 reduced the frequency (≈34 %) and amplitude (≈26 %) of spontaneous IPSCs (sIPSCs) recorded in Purkinje cells, one of the principal synaptic targets of basket neurones. 6 This is the first report of an I h current in mammalian inhibitory presynaptic terminals, which may be an important target for neuromodulation in the cerebellum. Comparing the biophysical properties and distribution of cloned hyperpolarization‐activated cation channels, we also suggest a molecular candidate underlying I h at these synapses.