title: Roles of mitochondria and temperature in the control of intracellular calcium in adult rat sensory neurons.
abstract: We recorded Ca2+ current and intracellular Ca2+ ([Ca2+](i)) in isolated adult rat dorsal root ganglion (DRG) neurons at 20 and 30 degrees C. In neurons bathed in tetraethylammonium and dialyzed with cesium, warming reduced resting [Ca2+](i) from 87 to 49 nM and the time constant of the decay of [Ca2+](i) transients (tau(r)) from 1.3 to 0.99s (Q(10)=1.4). The Buffer Index, the ratio between Ca2+ influx and Delta[Ca2+](i) (f I(ca)d(t)/Delta[Ca2+]i) , increased two- to threefold with warming. Neither inhibition of the plasma membrane Ca2+ -ATPase by intracellular sodium orthovanadate nor inhibition of Ca2+ uptake by the endoplasmic reticulum by thapsigargin plus ryanodine were necessary for the effects of warming on these parameters. In contrast, inhibition of the mitochondrial Ca2+ uniporter by intracellular ruthenium red largely reversed the effects of warming. Carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP, 500 nM) increased resting [Ca2+](i) at 30 degrees C. Ten millimolar intracellular sodium prolonged the recovery of [Ca2+](i) transients to 10-40s. This effect was reversed by an inhibitor of mitochondrial Na(+)/Ca2+ -exchange (CGP 37157, 10 microM). Thus, mitochondrial Ca2+ uptake is necessary for the temperature-dependent increase in Ca2+ buffering and mitochondrial Ca2+ fluxes contribute to the control of [Ca2+](i) between 50 and 150 nM at 30 degrees C.
authors: Department of Physiology & Cell Biology/MS 352, University of Nevada School of Medicine, Reno, NV 89557, USA.
authors: S H
authors: SH
authors: Kang
authors: A
authors: A
authors: Carl
authors: J M
authors: JM
authors: McHugh
authors: H R
authors: HR
authors: Goff
authors: J L
authors: JL
authors: Kenyon
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D013696:Temperature; D014475:Uncoupling Agents / Q000378:metabolism
chemical_list: D019831:Sodium-Calcium Exchanger; D014475:Uncoupling Agents; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D012964:Sodium; D000252:Calcium-Transporting ATPases; D002118:Calcium
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