Fig. 1.

Calcium-dependent exocytosis in NK cells. (a) Example traces of C_m increase (ΔC_m), G_s, and G_m from three cells patched with 0.1, 3, and 60 μM free Ca²⁺ in the pipette solution ([Ca²⁺]_p), respectively. (b) The averaged total ΔC_m values are plotted against [Ca²⁺]_p (n = 13–23). The line represents a fit using a logistic equation, which gives an EC₅₀ of 4.5 μM. (c) Example ΔC_m traces from resting and PEC-activated NK cells demonstrating dramatic augmentation of the secretory response after PEC stimulation. (d) The mean ± SEM values (n = 11–27) from resting cells recorded with 0.1 and 40 μM [Ca²⁺]_p and 40 μM GTPγS are compared with that of PEC-activated NK cells stimulated with 40 μM [Ca²⁺]_p and 40 μM GTPγS.