Hydrogen peroxide attenuates refilling of intracellular calcium store in mouse pancreatic acinar cells

Abstract

Intracellular calcium (Ca2+) oscillation is an initial event in digestive enzyme secretion of pancreatic acinar cells. Reactive oxygen species are known to be associated with a variety of oxidative stress-induced cellular disorders including pancreatitis. In this study, we investigated the effect of hydrogen peroxide (H2O2) on intracellular Ca2+ accumulation in mouse pancreatic acinar cells. Perfusion of H2O2 at 300 µM resulted in additional elevation of intracellular Ca2+ levels and termination of oscillatory Ca2+ signals induced by carbamylcholine (CCh) in the presence of normal extracellular Ca2+. Antioxidants, catalase or DTT, completely prevented H2O2-induced additional Ca2+ increase and termination of Ca2+ oscillation. In Ca2+-free medium, H2O2 still enhanced CCh-induced intracellular Ca2+ levels and thapsigargin (TG) mimicked H2O2-induced cytosolic Ca2+ increase. Furthermore, H2O2-induced elevation of intracellular Ca2+ levels was abolished under sarco/endoplasmic reticulum Ca2+ ATPase-inactivated condition by TG pretreatment with CCh. H2O2 at 300 µM failed to affect store-operated Ca2+ entry or Ca2+ extrusion through plasma membrane. Additionally, ruthenium red, a mitochondrial Ca2+ uniporter blocker, failed to attenuate H2O2-induced intracellular Ca2+ elevation. These results provide evidence that excessive generation of H2O2 in pathological conditions could accumulate intracellular Ca2+ by attenuating refilling of internal Ca2+ stores rather than by inhibiting Ca2+ extrusion to extracellular fluid or enhancing Ca2+ mobilization from extracellular medium in mouse pancreatic acinar cells.

Hydrogen peroxide inhibits Ca2+ efflux through plasma membrane Ca2+-ATPase in mouse parotid acinar cells

“…In this study, when parotid acinar cells were exposed to 1 mM H 2 O 2 in normal Ca 2+ buffer, there was a significant intracellular Ca 2+ accumulation, and the elevated Ca 2+ was nearly returned to baseline after the cessation of H 2 O 2 perfusion. Generally, H 2 O 2 is known to accumulate cytosolic Ca 2+ without acute cell death at concentrations from 10 µM to 5 mM in various cell types [ 16 17 18 19 20 21 22 23 24 25 ]. Thus, mouse parotid acinar cells are thought to be relative resistance to H 2 O 2 .…”

“…In fact, it has been reported that functionally important sulfhydryl group are present within PMCA and SERCA molecules that is localized within the catalytic and controlling centers of Ca 2+ -ATPase [ 38 39 40 ]. We previously reported that H 2 O 2 accumulates intracellular Ca 2+ by attenuating SERCA activity in pancreatic acinar cells [ 25 ]. Interestingly, in this study, H 2 O 2 failed to change Ca 2+ refilling into the ER store through SERCA by the application of Ca 2+ and Mg-ATP in permeabilized parotid acinar cells.…”

“…However, the imbalanced states by excessive production of ROS or reduction of antioxidants leading to morphological and functional damage of cells [ 15 ]. Although hydrogen peroxide-induced oxidative stress are correlated with overloaded intracellular Ca 2+ levels, the mechanism of sustained Ca 2+ overload has still been unclear due to cell-to-cell difference in Ca 2+ transport molecules as shown by the following evidence: 1) The enhanced Ca 2+ release from intracellular store [ 16 17 18 ], 2) The stimulated Ca 2+ entry from extracellular medium [ 19 20 21 22 ] and 3) The attenuated Ca 2+ efflux by inactivation of plasma membrane Ca 2+ -ATPase (PMCA) or sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA) [ 23 24 25 ] in various cell types. In the present study, we have therefore characterized the effect of hydrogen peroxide on intracellular Ca 2+ signals and the underlying mechanism of Ca 2+ accumulation in mouse parotid acinar cells.…”

Reactive Oxygen Species and Endothelial Ca2+ Signaling: Brothers in Arms or Partners in Crime?

“…Indeed, an increase in the rate of ER Ca 2+ refilling by SERCA2B would lead to ER Ca 2+ overload, which, in turn, is able to stimulate InsP 3 Rs and thereby initiate the function cross-talk between STIM and Orai proteins [ 195 ]. Paradoxically, SERCA2B inhibition by excessive production of oxidants could lead to SOCE activation as intraluminal Ca 2+ efflux through ER leakage channels is no longer counteracted by SERCA2B-mediated sequestration into ER lumen and may lead to ER Ca 2+ depletion [ 33 , 196 ].…”