FIGURE 5.

NHA2 protects against acid suicide. A, model depicting the acid suicide experiment. B, control and NHA2-overexpressing MDCK cells were loaded with 90 mm Li⁺ as described under “Experimental Procedures,” then washed with choline chloride (pH 7.4) buffer and transferred to 90 mm choline chloride acid solution (pH 5.5) for 1 h. Cell survival was measured by MTS assay. C, acid suicide study in the presence of NHE and NHA2 agonists, a similar protocol as in B was adopted but the cells were pretreated with 200 μm amiloride or phloretin for 1 h prior to Li⁺ loading. Amiloride or phloretin were also present during the lithium loading and in the choline chloride solution. Cell survival was measured by MTS assay. Mean ± S.D. is shown for all data.