title: Micromolar Ca2+ transients in dendritic spines of hippocampal pyramidal neurons in brain slice.
abstract: The magnitude and dynamics of [Ca2+] changes in spines and dendrites of hippocampal CA1 pyramidal neurons have been characterized using a low affinity fluorescent indicator, mag-Fura 5, that is sensitive to Ca2+ in the micromolar range. During tetanic stimulation (1 s), we observed progressive [Ca2+] increases in distal CA1 spines to as much as 20-40 microM, both in organotypic slice culture and acute slice. Similar accumulations were reached during continuous depolarization (+10 mV, 1 s) when K+ channels had been blocked, but not with spike trains driven by postsynaptic current injection. The large [Ca2+] increases due to tetanic stimulation were blocked by APV, indicating that NMDA receptor-dependent influx was critical for the large responses. These findings have significant implications for low affinity Ca(2+)-dependent biochemical processes and show a new upper limit for [Ca2+] changes measured in these neurons during stimulation.
authors.affiliation: Roche Institute of Molecular Biology, Roche Research Center, Nutley, New Jersey 07110, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Petrozzino
authors.forename: L D
authors.initials: LD
authors.lastname: Pozzo Miller
authors.forename: J A
authors.initials: JA
authors.lastname: Connor
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D046508:Culture Techniques; D003712:Dendrites / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D004558:Electric Stimulation; D004594:Electrophysiology; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D006624:Hippocampus / Q000648:ultrastructure*; D009474:Neurons / Q000378:metabolism*; D026902:Potassium Channel Blockers; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013569:Synapses / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes; D026902:Potassium Channel Blockers; D016194:Receptors, N-Methyl-D-Aspartate; C094537:mag-Fura 5; D004533:Egtazic Acid; D015763:2-Amino-5-phosphonovalerate; D002118:Calcium; D016257:Fura-2