SBP, BNP, and heart calcium channels. A, SBP measured in unanesthetized male mice (n = 7–9) from 3–12 months of age. Cardiac LV BNP RNA levels were measured at 6 (B) and 12 (C) months of age (n = 5–9). Circulating BNP levels were measured by ELISA at 5 (D) and 7 (E) months of age (n = 7–9). RNA levels of the major calcium channels in heart were measured at 6 months (F) and 12 months (G) of age. All values are presented as average ± SEM. *, Significant difference between genotype (P < .05); †, significant interaction between age and genotype (P < .05); ‡, significant difference with age (P < .05); SERCA2, sarcoplasmic endoreticulum calcium exchanger 2; LTCC, L-type calcium channel, NCX1, sodium calcium exchanger 1; RYR2, ryanodine receptor 2.