1. MgATP-dependent Ca2+ uptake by rat liver microsomal preparations and permeabilized hepatocytes was measured in the presence or absence of Pi. 2. Monitoring of free Ca2+ in incubation systems with a Ca2+ electrode in the presence of Pi (2-7 mM) revealed a biphasic Ca2+ uptake, with the onset of a second, Pi-dependent, Ca2+ accumulation. 3. Increasing Pi concentrations (up to 10 mM) caused a progressive enlargement of 45Ca2(+)-loading capacity of microsomal fractions. 4. As a result of Pi stimulation of active Ca2+ uptake, [32P]Pi and 45Ca2+ were co-accumulated. 5. Experiments with permeabilized hepatocytes revealed that the amount of Ca2+ releasable by myo-inositol 1,4,5-trisphosphate is unaffected by Pi.
MgATP-dependent accumulation of calcium ions and inorganic phosphate in a liver reticular pool
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R Fulceri, G Bellomo, A Gamberucci, A Benedetti; MgATP-dependent accumulation of calcium ions and inorganic phosphate in a liver reticular pool. Biochem J 1 December 1990; 272 (2): 549–552. doi: https://doi.org/10.1042/bj2720549
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