TY - JOUR
T1 - Extracellular Ca2+ increases cytosolic free Ca2+ in freshly isolated rat odontoblasts
AU - Guo, Liang
AU - Davidson, Robert M.
PY - 1999
Y1 - 1999
N2 - Recent evidence suggests that extracellular Ca2+ may modulate cell function in mineralized tissue. To determine whether dentinogenic cells, in particular, are sensitive to extracellular Ca2+, fura-2 microfluorometry was used to monitor intracellular calcium levels in odontoblasts freshly isolated from rat incisor. In response to applications of 0.5-4.0 mM extracellular calcium (CaCl2), most odontoblasts (84 %; 107/128) showed an increase in intracellular calcium. For the majority of these cells (70%; 75/107), the typical response was biphasic; there was an initial, transient increase in intracellular calcium which reached peak levels within 30-50 s and decayed rapidly, followed by a slower (> 300 s) recovery toward basal levels. In general, the response of these cells to calcium was repeatable and the mean calcium concentration for the half-maximal response was ~1.3 mM. This effect could be partially blocked by either 200 μM lanthanum, a nonspecific blocker of Ca2+ channels, or 20 μM dantrolene, a potent inhibitor of Ca2+ release from internal stores. Used in combination, lanthanum, and dantrolene nearly abolished the calcium response completely. In addition, this response was sensitive to the dihydropyridine-sensitive calcium channel blocking agent nicardipine (60 μM), indicating a role for voltage-gated calcium channels during these events. These results show that odontoblasts respond to external calcium through mechanisms involving both influx of external calcium as well as release of calcium from internal stores and suggest a role for extracellular calcium in regulating the function of these cells.
AB - Recent evidence suggests that extracellular Ca2+ may modulate cell function in mineralized tissue. To determine whether dentinogenic cells, in particular, are sensitive to extracellular Ca2+, fura-2 microfluorometry was used to monitor intracellular calcium levels in odontoblasts freshly isolated from rat incisor. In response to applications of 0.5-4.0 mM extracellular calcium (CaCl2), most odontoblasts (84 %; 107/128) showed an increase in intracellular calcium. For the majority of these cells (70%; 75/107), the typical response was biphasic; there was an initial, transient increase in intracellular calcium which reached peak levels within 30-50 s and decayed rapidly, followed by a slower (> 300 s) recovery toward basal levels. In general, the response of these cells to calcium was repeatable and the mean calcium concentration for the half-maximal response was ~1.3 mM. This effect could be partially blocked by either 200 μM lanthanum, a nonspecific blocker of Ca2+ channels, or 20 μM dantrolene, a potent inhibitor of Ca2+ release from internal stores. Used in combination, lanthanum, and dantrolene nearly abolished the calcium response completely. In addition, this response was sensitive to the dihydropyridine-sensitive calcium channel blocking agent nicardipine (60 μM), indicating a role for voltage-gated calcium channels during these events. These results show that odontoblasts respond to external calcium through mechanisms involving both influx of external calcium as well as release of calcium from internal stores and suggest a role for extracellular calcium in regulating the function of these cells.
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U2 - 10.1359/jbmr.1999.14.8.1357
DO - 10.1359/jbmr.1999.14.8.1357
M3 - Article
C2 - 10457268
AN - SCOPUS:0032588693
SN - 0884-0431
VL - 14
SP - 1357
EP - 1366
JO - Journal of Bone and Mineral Research
JF - Journal of Bone and Mineral Research
IS - 8
ER -