Extended Data Figure 7: Elevated [K⁺]_e does not permanently affect T cell [K⁺]_i, V_m, or subsequent response to K⁺-induced suppression of effector function.

a, Flow cytometry-based calibration of [K⁺]_i. For all values cells were treated with 50 μM gramicidin in titrated doses of [K⁺]_e to provide a known [K⁺]_i. b, Intra-experimental quantification of [K⁺]_i in control conditions and elevated [K⁺]_e based on calibration from a. c, Flow cytometry analysis of the relative V_m of CD8⁺ T cells of the indicated origin using DiSBAC₄(3). d, Cells of the indicated origin assayed in the indicated conditions as in c. e, Flow cytometry analysis of relative [K⁺]_i of CD8⁺ T cells of the noted origin washed and assayed in indicated conditions, quantified by relative fluorescence of Asante-Green 4. f, Compiled analysis of relative IFNγ production by CD8⁺cells of the indicated origin washed and subjected to TCR stimulation in the indicated conditions. Centre values and error bars represent mean ± s.e.m. NS, not significant, between experimental and control conditions as assessed by two-tailed Student’s t-test (c) or two-way ANOVA (d–f). For chronic conditioning, additional [K⁺]_e = 40 mM, n = 3 technical (a–e) or culture (f) replicates per condition. a–f, Representative of two independent experiments.