Assays

The potassium influx after the addition of a certain amount of KCl to a potassium free medium, followed by the injection of glucose will be measured by using the MIFE and FLISE technique. This reveals a time course of potassium. Also the external potassium concentrations will be measured.

In parallel with the potassium influx the efflux of protons is monitored by measuring the external proton concentration changes with MIFE or FLISE.

Further fluxes (ammonium, chloride, calcium) will be measured dependent on the capacities of the MIFE/FLISE technique.

The external potassium changes will be monitored by the MIFE and FLISE technique. This allows an estimation of internal potassium changes by determining an initial concentration.

The external pH changes will be monitored by the MIFE and FLISE technique. This allows an estimation of internal pH changes by determining an initial pH. pH changes will be also determined by using green fluorescent protein dyes. Relating the proton efflux and the change of internal pH allows an estimate of the proton buffering capacity.