Calcium signalling in granule neurones studied in cerebellar slices.
The cytoplasmic free calcium concentration ([Ca2+]i) was studied in Fura-2/AM loaded granule neurones in acutely prepared cerebellar slices isolated from neonatal (6 days old) and adult (30 days old) mice. Bath application of elevated (10-50 mM) KCl-containing extracellular solutions evoked [Ca2+]i rise which was dependent on extracellular Ca2+. The K(+)-induced [Ca2+]i elevation was inhibited to different extends by verapamil, nickel and omega-conotoxin suggesting the coexpression of different subtypes of plasmalemmal voltage-gated Ca2+ channels. Bath application of caffeine (10-40 mM) elevated [Ca2+]i by release of Ca2+ from intracellular stores. Caffeine-induced [Ca2+]i elevation was inhibited by 100 microM ryanodine and 500 nM thapsigargin. Depletion of internal Ca2+ stores by caffeine, or blockade of Ca2+ release channels by ryanodine, did not affect depolarization-induced [Ca2+]i transients, suggesting negligible involvement of Ca(2+)-induced Ca2+ release in [Ca2+]i signal generation following cell depolarization. External application of 100 microM glutamate, but not acetylcholine (1-100 microM), carbachol (10-100 microM) or (1S,3R)-ACPD (100-500 microM) evoked [Ca2+]i elevation. Part of glutamate-triggered [Ca2+]i transients in neurones from neonatal mice was due to Ca2+ release (presumably via inositol-(1,4,5)-trisphosphate-sensitive mechanisms) from internal Ca2+ stores. In adult animals, glutamate-triggered [Ca2+]i elevation was exclusively associated with plasmalemmal Ca2+ influx via both voltage-gated and glutamate-gated channels.
Kirischuk
S
S
Bogomoletz Institute of Physiology and International Centre of Molecular Physiology, Kiev, Ukraine.
Voitenko
N
N
Kostyuk
P
P
Verkhratsky
A
A
D000109:Acetylcholine / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000819:agonists / Q000502:physiology*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002531:Cerebellum / Q000166:cytology*; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004553:Electric Conductivity; D004594:Electrophysiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018846:Excitatory Amino Acids / Q000494:pharmacology; D006706:Homeostasis / Q000502:physiology; D015640:Ion Channel Gating / Q000502:physiology; D051379:Mice; D008808:Mice, Inbred CBA; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000502:physiology*; D009498:Neurotoxins / Q000494:pharmacology; D009924:Organ Culture Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D016318:Quisqualic Acid / Q000494:pharmacology; D012680:Sensitivity and Specificity; D015398:Signal Transduction / Q000502:physiology
D002120:Calcium Channel Agonists; D018690:Excitatory Amino Acid Agonists; D018846:Excitatory Amino Acids; D009498:Neurotoxins; D010726:Phosphodiesterase Inhibitors; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D002110:Caffeine; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D000109:Acetylcholine; D002118:Calcium