Figure 2. Heart function was measured by M-mode trace. (A) Heart period. (B) Heart systolic period. (C) Heart diastolic period. (D) Heart diastolic dysfunction index. The diastolic dysfunction index is diastolic interval standard deviation/diastolic interval median). (E) Fractional shortening. (F) Diastolic diameter. (G) Systolic diameter. (H) Microscopic image of cardiac function from M-mode trace in 5-week-old and 7-week-old Drosophila. 1: 5-week-old hand-Gal4>w11118 flies; 2: 5-week-old hand-Gal4>UAS-dSir2-RNAi flies; 3: 7-week-old hand-Gal4>w11118 flies; 4: 7-week-old hand-Gal4>UAS-dSir2-RNAi flies. It can be observed from 1, 2, 3, and 5 that the cardiac dSir2 knockdown could reduce heart period and fractional shortening, and increase diastolic dysfunction. Independent-sample t tests were used to assess differences between the 1-week-old” and 7-week-old flies to explore the effects of aging on the heart. Independent-sample t tests were used to assess differences between the hand-Gal4>w11118 and hand-Gal4>UAS-dSir2-RNAi flies to explore the effects of cardiac dSir2 knockdown on the heart. Data are represented as means ± SEM. *P<0.05; **P <0.01. Sample size was 30 hearts for each group.