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The retrograde inhibition of IPSCs in rat cerebellar Purkinje cells is highly sensitive to intracellular Ca 2+
Author(s) -
Glitsch Maike,
Parra Paula,
Llano Isabel
Publication year - 2000
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2000.00994.x
Subject(s) - bapta , egta , biophysics , inhibitory postsynaptic potential , chemistry , exocytosis , depolarization , postsynaptic potential , postsynaptic current , cerebellum , intracellular , calcium , biochemistry , neuroscience , biology , receptor , membrane , organic chemistry
The Ca 2+ ‐dependent retrograde inhibition of inhibitory postsynaptic currents (depolarization‐induced‐suppression of inhibition; DSI) was investigated using fura‐2 Ca 2+ measurements and whole‐cell patch‐clamp recordings in rat cerebellar Purkinje cells. DSI was studied in cells loaded with different concentrations of the Ca 2+ chelators BAPTA and EGTA. A concentration of 40 m m BAPTA was required to significantly interfere with DSI, whereas 10 m m BAPTA was almost ineffective. 40 m m EGTA reduced DSI, but was less effective than 40 m m BAPTA. Ratiometric Ca 2+ measurements indicated that the extent of DSI depended critically on the changes in intracellular calcium ([Ca 2+ ] i ). The relationship between DSI and peak Δ[Ca 2+ ] i could be approximated by a hyperbolic function, with apparent half‐saturation concentrations of 200 and 40 n m for dendritic and somatic [Ca 2+ ] i , respectively. It is suggested that DSI is due to somatodendritic exocytosis of a retrograde messenger, and that this exocytosis is highly sensitive to [Ca 2+ ] i .