Lithium is well established as a treatment of manic-depressive illness. As for the mechanism of action of lithium, it is proposed that lithium has effects on intracellular calcium ion (Ca2+) movement. But there are few reports in which the effects of lithium on intracellular Ca2+ movement are observed in the mammalian brain. We therefore examined the effects of lithium on intracellular Ca2+ changes in the rat hippocampal slices with a Ca2+ sensitive dye fura-2, and analyzed by means of a fluorescence microscope, a video-camera and photometrical devices. From the results of treatment with various noradrenergic agonists or antagonists, noradrenaline (NA)-induced intracellular Ca2+ change appears to be mainly mediated by alpha 1-adrenoceptors (AR) rather than alpha 2- or beta-AR. Furthermore, they are considered to be mediated by both alpha 1A-AR and alpha 1B-AR, and to be partly dependent on extracellular Ca2+. Lithium decreased NA-induced intracellular Ca2+ mobilization by attenuation of T1/2 rather than a change in the peak value, and antagonized ouabain-induced intracellular Ca2+ increase. Lithium may therefore suppress intracellular Ca2+ movement by enhancing the extrusion of intracellular Ca2+.