Intraneuronal Ca2+ stores act mainly as a 'Ca2+ sink' in cerebellar granule neurones.
The role of intracellular Ca2+ stores during depolarization-evoked Ca2+ signals in cultured cerebellar granule neurones was assessed by depletion of the stores with a specific inhibitor of the endoplasmic reticulum Ca2+ pump: thapsigargin (TG, 0.7 microM). The maximal rate of [Ca2+]i increase, measured as the first-order differential of the [Ca2+]i trace, increased directly in proportion to the increasing KCl concentration (in the range 20-90 mM) or, for a given KCl concentration (50 mM), to the levels of pre-stimulation [Ca2+i (range 25-100 nM Ca2+). Both these relationships were unaffected by TG. In contrast, the amplitude of the KCl-evoked response for KCl concentrations > 30 mM (inducing an increase in [Ca2+]i > 400 nM) was increased in the presence of TG.
Toescu
E C
EC
Department of Physiology, Birmingham University Medical School, UK.
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D011189:Potassium Chloride; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases