It is well known that chromaffin cells of adrenal medulla secrete catecholamine in response to sympathetic nerve activation and the influx of Ca²⁺ through the voltage dependent Ca²⁺ channels (VDCC) in the cell membrane do a major role in this secretory process. In this study, we explored the effect of divalent cations on VDCC of rat chromaffin cells. Rat (Sprague-Dawley rat, 150-250 gm) chromaffin cells were isolated and cultured. Standard giga seal, whole cell recording techniques were employed to study Ca²⁺ current with external and internal solutions that could effectively isolate VDCC currents (NMG in external and TEA and Cs²⁺ in internal solution). The voltage dependence and the inactivation time course of VDCC in our cells were identical to those of bovine chromaffin cells. A persistent inward current was first activated by depolarizing step pulse from the holding potential (H.P.) of -80 mV to -40 mV, increased to maximum amplitude at around +10 mV, and became smaller with progressively higher depolarizing pulses to reverse at around +60 mV. The inactivation time constant (τ), fitted from the long duration test potential (2 sec) was 1295.2±126.8 msec (n=20, 1 day of culture, mean ±S.E.M.) and the kinetic parameters were not altered along the culture duration. Nicardipine (10 μM) blocked the current almost completely. Among treated divalent cations such as Cd²⁺, Co²⁺, Ni²⁺, Zn²⁺ and ,Mn²⁺, Cd²⁺ was the most potent blocker on VDCC. When the depolarizing step pulse from -80 mV to 10 mV was applied, the equilibrium dissociation constant (K_d) of Cd²⁺ was 39 μM, K_d of Co²⁺ was 100 μM and K_d of Ni²⁺];was];780μM. The principal findings of this study are as follows. First, the majority of Ca²⁺ channels in rat chromaffin cells are well classified to L-type Ca²⁺ channel in the view of kinetics and pharmacology. Second, all divalent cations tested could block the Ca²⁺ current and the most potent blocker among the tested was Cd²⁺.