The total and ouabain-dependent rate constants of efflux of zinc (Zn) ions from lymphocytes isolated from healthy subjects were measured in vitro in an environment containing calcium (Ca) and magnesium (Mg) ions. Both the total (ERCt-Zn) and ouabain-dependent (ERCos-Zn) rate constants were higher in the presence of Mg2+, with the the oubain-dependent efflux significantly different 0.29+/-0.07 vs 0.13+/-0.02 with and without Mg2+, respectively (p<0.001). After the addition of verapamil, an increase of ERCE-Zn was observed in both ionic environments and was higher and statistically significant in the presence of Mg2+: 1.94+/-0.64 vs 2.97+/-1.16 (p<0.025). These results suggest that verapamil has an enhancing effect on Zn efflux from isolated lymphocytes, suggesting that calcium channel blockers might result in better Zn homeostatic regulation in diseases of the cardiovascular system.