Cytoplasmic Ca2+ at low submicromolar concentration stimulates mitochondrial metabolism in rat luteal cells

György Szabadkai, János G. Pitter, András Spät

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

The cytoplasmic Ca2+ signal is transferred to the mitochondrial matrix and activates mitochondrial dehydrogenases. The requirement for supramicromolar cytoplasmic [Ca2+] ([Ca2+]i) in perimitochondrial micro-domains in this response has been suggested. We studied the correlation between [Ca2+]i, mitochondrial [Ca2+] ([Ca2+]m) and mitochondrial formation of reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] in the presence of submicromolar [Ca2+]i in cultured rat "large" luteal cells. [Ca2+]i was monitored fluorimetrically with fura-PE3, [Ca2+]m with rhod-2 and NAD(P)H with autofluorescence. In intact cells, prostaglandin F, which induces both intracellular Ca2+ release and Ca2+ entry, stimulated mitochondrial NAD(P)H formation. Thapsigargin-induced Ca2+ release and subsequent capacitative Ca2+ entry, both resulting in Ca2+ responses not exceeding 150-200 nM, also enhanced the reduction of pyridine nucleotides. As shown in inhibitor studies, the increased steady-state NAD(P)H level was due to activation of Ca2+-dependent dehydrogenases. [Ca2+]m, measured in permeabilized cells, increased moderately, but significantly, following elevation of [Ca2+]i from 50 to 180 nM, showed a further gradual increase at higher submicromolar [Ca2+]i values and rose steeply at supramicromolar [Ca2+]i. In summary, our results demonstrate that, in a steroid-producing cell type, net mitochondrial Ca2+ uptake and mitochondrial dehydrogenation can be activated even by low submicromolar increases of [Ca2+]i.

Original languageEnglish
Pages (from-to)678-685
Number of pages8
JournalPflugers Archiv European Journal of Physiology
Volume441
Issue number5
DOIs
Publication statusPublished - Mar 12 2001

Keywords

  • Ca signal
  • Luteal cell
  • Mitochondrial Ca concentration
  • Reduced pyridine nucleotides

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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