Determination of alteration of intracellular potassium level by using simple device.

We have hypothesized that increased concentration of potassium ion (K+) in the cytoplasm determines the degree of mitochondrial depolarization and enhancement of cytotoxicity and is an important factor in determining neuronal cell death. The definition of intracellular ion concentration is possible using the patch clamp method, while the equipment is expensive. Fluorescence indicators for various ions are still in the development stage. In this study, we investigated whether it is possible to define intracellular and extracellular K+ concentrations and chase alterations in intracellular K+ concentrations using a simple K+ meter. A calibration curve of K+ concentration-ppm was prepared with a potassium chloride solution. We could determine the K+ concentration in tissue homogenates from several brain regions, and it was found that the K+ concentration per tissue weight was almost constant. It was found that when the cell suspension or the medium of adherent cells was changed to a medium containing no K+, the intracellular K+ concentration decreased. Also in the medium containing a high concentration of K+, the intracellular K+ concentration increased. The medium of the cell suspension and adherent cells was changed to a medium containing valinomycin, which is a K+ ionophore, or VU0463271, which is a K+, Cl- cotransporter inhibitor, however no change in intracellular K+ concentration was observed. In the next, we will investigate using drugs that more directly change the intracellular K+ concentration (eg, K + channel opener).