Agonist-stimulated calcium transients in PC12 cells are affected differentially by cadmium and nickel

Rat pheochromocytoma (PC12) cells were loaded with the fluorescent indicator Fura-2 and the effects of cadmium and nickel on the mobilization of calcium elicited by bradykinin and external ATP were studied. Cadmium and nickel ions provoked a concentration-dependent decrease of the initial peak and/or the subsequent plateau phase of bradykinin-induced Ca2+ transients in a different manner: whereas cadmium (0.5-2.5 microM) diminished the calcium peak without modifying the sustained plateau, nickel (25-1000 microM) only slightly lowered the peak but markedly decreased the plateau phase. In the case of ATP-stimulated calcium transients, which are without a sustained plateau, both cadmium and nickel ions decreased the peak signal. Possible consequences are discussed in terms of a disturbance of hormone-stimulated cell activation by cadmium and nickel.