KCNJ8 and heart failure: Despite the effect of an increased afterload and coronary spasm seen previously in Kir6.1 knockout,16 and cardiac hypertrophy/heart failure phenotypes described in Kir6.2 knockout animals,17 there were no differences in cell capacitance (surrogate for cell size) of AMs from WT, 6.1-gKO, and 6.2-gKO mice at this age (Figure S3).