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Intracellular Calcium Dynamics and Cellular Energetics in Ischemic NG108‐15 Cells Studied by Concurrent 31 P/ 19 F and 23 Na Double‐Quantum Filtered NMR Spectroscopy
Author(s) -
Tauskela Joseph S.,
Shoubridge Eric A.
Publication year - 1996
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1996.66010266.x
Subject(s) - intracellular , chemistry , intracellular ph , phosphocreatine , depolarization , biophysics , cytosol , antiporter , ischemia , calcium , nifedipine , calcium in biology , biochemistry , medicine , endocrinology , biology , energy metabolism , membrane , organic chemistry , enzyme
The role of voltage‐sensitive Ca 2+ channels in mediating Ca 2+ influx during ischemia was investigated in NG108‐15 cells, a neuronal cell line that does not express glutamate‐sensitive receptor‐mediated Ca 2+ channels. Concurrent 31 P/ 19 F and 23 Na double‐quantum filtered (DQF) NMR spectra were used to monitor cellular energy status, intracellular [Ca 2+ ] ([Ca 2+ ] i ), and intracellular Na + content in cells loaded with the calcium indicator 1,2‐bis‐(2‐amino‐5‐fluorophenoxy)ethane‐ N,N,N′,N′ ‐tetraacetic acid (5FBAPTA) during ischemia and reperfusion. Cells loaded with 5FBAPTA were indistinguishable from unloaded cells except for small immediate decreases in levels of phosphocreatine (PCr) and ATP. Ischemia induced a steady decrease in intracellular pH and PCr and ATP levels, and a steady increase in intracellular Na + content; however, a substantial increase in [Ca 2+ ] i (about threefold) was seen only following marked impairment of cellular energy status, when PCr was undetectable and ATP content was reduced to 55% of control levels. A depolarization‐induced increase in [Ca 2+ ] i could be completely blocked by 1 µ M nifedipine, whereas up to 20 µ M nifedipine had no effect on the increase in [Ca 2+ ] i seen during ischemia. These data demonstrate that voltage‐gated Ca 2+ channels do not mediate significant Ca 2+ flux during ischemia in this cell line and suggest an important role for Ca 2+ i stores, the Na + /Ca 2+ antiporter, or other processes linked to cellular energy status in the increase in cytosolic Ca 2+ level during ischemia.