Role of mitochondria in Ca(2+) homeostasis of mouse pancreatic acinar cells.
The effects of mitochondrial Ca(2+) uptake on cytosolic Ca(2+) concentration ([Ca(2+)](c)) were investigated in mouse pancreatic acinar cells using cytosolic and/or mitochondrial Ca(2+) indicators. When calcium stores of the endoplasmic reticulum (ER) were emptied by prolonged incubation with thapsigargin (Tg) and acetylcholine (ACh), small amounts of calcium could be released into the cytosol (Delta[Ca(2+)](c)=46 +/- 6 nM, n=13) by applying mitochondrial inhibitors (combination of rotenone (R) and oligomycin (O)). However, applications of R/O, soon after the peak of Tg/Ach-induced Ca(2+) transient, produced a larger cytosolic calcium elevation (Delta[Ca(2+)](c)=84 +/- 6 nM, n=9), this corresponds to an increase in the total mitochondrial calcium concentration ([Ca(2+)](m)) by approximately 0.4 mM. In cells pre-treated with R/O or Ru360 (a specific blocker of mitochondrial Ca(2+) uniporter), the decay time-constant of the Tg/ACh-induced Ca(2+) response was prolonged by approximately 40 and 80%, respectively. Tests with the mitochondrial Ca(2+) indicator rhod-2 revealed large increases in [Ca(2+)](m) in response to Tg/ACh applications; this mitochondrial uptake was blocked by Ru360. In cells pre-treated with Ru360, 10nM ACh elicited large global increases in [Ca(2+)](c), compared to control cells in which ACh-induced Ca(2+) signals were localised in the apical region. We conclude that mitochondria are active elements of cellular Ca(2+) homeostasis in pancreatic acinar cells and directly modulate both local and global calcium signals induced by agonists.
Johnson
P R
PR
MRC Secretory Control Research Group, Physiological Laboratory, University of Liverpool, Liverpool, UK.
Tepikin
A V
AV
Erdemli
G
G
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000172:deficiency*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2; D006575:Heterocyclic Compounds, 3-Ring; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism*; D017975:Ruthenium Compounds / Q000494:pharmacology
D005456:Fluorescent Dyes; D006575:Heterocyclic Compounds, 3-Ring; C112020:Ru 360; D017975:Ruthenium Compounds; C068483:rhod-2; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2