Measurements of cytosolic free Ca2+ concentrations in odontoblasts.
To investigate the responsiveness of odontoblasts to electrical and mechanical stimuli, the concentrations of cytosolic free Ca2+ ([Ca2+]i) were measured using fura-2 microfluorometry in slice preparations of rat dental pulp. [Ca2+]i under resting conditions (basal [Ca2+]i) were 258.0 +/- 37.7 nM (mean +/- S.E., n = 113). The basal [Ca2+]i of the odontoblasts with remarkably active responses to stimuli were 221.0 +/- 81.1 nM (mean +/- S.E., range: 16-685 nM). Depolarization by high extracellular K+ concentration ([K+]o) caused a rapid increase in [Ca2+]i. The depolarization-induced increase in [Ca2+]i was enhanced by caffeine. The intense depolarization elicited [Ca2+]i oscillation in odontoblasts, which was enhanced by caffeine and suppressed by dantrolene. Hypotonic stimulation also induced an increase in [Ca2+]i of odontoblasts. The results indicate that the odontoblast possesses voltage-dependent Ca2+ channels, caffeine-sensitive Ca2+ stores and mechanosensitive cation channels.
Shibukawa
Y
Y
Department of Physiology, Tokyo Dental College, Chiba, Japan.
Suzuki
T
T
D000818:Animals; D002118:Calcium / Q000032:analysis*; D003592:Cytophotometry / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D003600:Cytosol / Q000737:chemistry* / Q000502:physiology; D003782:Dental Pulp / Q000166:cytology; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D016257:Fura-2; D007180:Incisor; D008334:Mandible; D008751:Methylene Blue; D008858:Microscopy, Phase-Contrast; D009804:Odontoblasts / Q000737:chemistry* / Q000502:physiology; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar
D005456:Fluorescent Dyes; D002118:Calcium; D008751:Methylene Blue; D016257:Fura-2