The influence of some organic compounds (pyridine, urea, chlorpyrifos, permethrin) and metal ions (Pb2+, Cd2-, Hg2+, Cu2+, Fe2+ and Zn2+) on Na+/K+-ATPase and Mg2+-ATpase activity isolated from rat brain synaptic plasma membranes (SPM) was investigated in order to develop a simple semi-quantitative and qualitative test method for selective detection of these analyites in aqueous solutions. The method is based on the spectrophotometric determination of inorganic ortho-phosphate (P-i) that serves as a measure of the enzymatic activity in the presence of various analytes. The concentration of P-p liberated by enzyme-catalysed hydrolysis of adenosinetriphosphate (ATP), by exposure to analytes was dose-dependent on the analyte concentration. Heavy metals (Pb, Cd, Hg, Cu, Fe and Zn), toxic organic compounds (pyridine, urea) and some pesticides (ehlorpyrifos, permethrin) showed diverse effects, inducing the inhibition or stimulation of the enzyme activity. Development of simple test method for simultaneous detection of the investigated analytes based on the variation of medium assay composition was discussed
