An Assay for the Rate of Removal of Extracellular Hydrogen Peroxide by Cells.
Cells have a wide range of capacities to remove extracellular hydrogen peroxide. At higher concentrations of extracellular H2O2(micromolar) the rate of removal can be approximated by a rate equation that is first-order in the concentration of H2O2and cell density. Here we present a method to determine the observed rate constant for the removal of extracellular H2O2on a per cell basis. In the cells examined, when exposed to 20 μM H2O2, these rate constants (kcell) range from 0.46 × 10-12s-1cell-1L for Mia PaCa-2 cells (human pancreatic carcinoma) to 10.4 × 10-12s-1cell-1L for U937 cells (human histiocytic lymphoma). For the relatively small red blood cellkcell= 2.9 × 10-12s-1cell-1L. These rate constants,kcell, can be used to compare the capacity of cells to remove higher levels of extracellular H2O2, as often presented in cell culture experiments. They also provide a means to estimate the rate of removal of extracellular H2O2, rate = -kcell[H2O2] (cells L-1), and the half-life of a bolus of H2O2. This information is essential to optimize experimental design and interpret data from experiments that expose cells to extracellular H2O2.
The University of Iowa, Free Radical and Radiation Biology Program & ESR Facility, Iowa City, IA 52242-1181, USA.
Brett A
BA
Wagner
Jordan R
JR
Witmer
Thomas Joost
TJ
van 't Erve
Garry R
GR
Buettner
Hydrogen peroxide; erythrocyte; kinetics; quantitative redox biology