Using fluorescence spectrometry and fluorecent probes we want to develop methods for the determination of the intracellular free metal ion concentration of Ca, Cd and Zn. These methods will be used to study the uptake kinetics and intracellular bindings of these metals. In the first place we want to investigate wether the metal ions are entering the cells via a common uptake system (calcium channels ?). Secondly, we want to determine at which intracellular free cadmium and/or zink concentrationsthe regulation of calcium is disturbed and wether metal acclimatisation influences these tresholds.