Cell calcium in human peripheral blood lymphocytes and the effect of mitogen

The apparent cell concentration of calcium in human peripheral blood lymphocytes is 143.3 +/- 17.7 microM, as measured by two different techniques using 45Ca. The steady-state level of accumulation, and possibly the rate of uptake, are increased in the presence of succinyl-concanavalin A. Initiation of the mitogen-induced alteration of cell calcium occurs within 1-2 min and the change is complete within 5-10 min. Determinations of cell calcium in cells suspended in low Na media indicate that (1) there is no difference in cell calcium between cells incubated in 142 mM extracellular Na and cells incubated in 63 mM extracellular Na, and (2) the mitogen-induced increase in cell calcium is unaffected by a decrease in extracellular sodium concentration (to 63 mM).