The calibration and use of a calcium ion-specific electrode for kinetic studies of mitochondrial calcium transport. |
| |
Authors: | R K Yamazaki D L Mickey M Story |
| |
Institution: | Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903, USA |
| |
Abstract: | A calcium ion-specific electrode has been used to study calcium transport by isolated,hepatic mitochondria. The methodology used requires only a sensitive pH meter operated in the millivolt mode with the electrode. Free calcium ion concentrations may be followed continuously. Using incubation conditions which cause release of intramitochondrial calcium, the calcium electrode system may also be used to determine total. intramitochondrial calcium. Techniques for the calibration of the electrode response are discussed. Free calcium ion concentrations have been calculated from total calcium concentrations and the association constants for the binding species present in the assay medium. The observation that the electrode response is linear to submicromolar concentrations allows calculation of a linear least-squares fit of millivolt reading to computed free calcium ion concentration. A computer program written in BASIC for these computations is included in Appendix material. The half-maximal rate constant for mitochondrial calcium uptake has been found to occur at a free calcium ion concentration of 6.5 μm. The interaction or Hill coefficient for the process is 2.3, indicating positive cooperativity. |
| |
Keywords: | To whom reprint requests should be addressed atthe Department of Pharmacology Wayne State University School of Medicine Detroit Mich 48201 |
本文献已被 ScienceDirect 等数据库收录! |