Objective      To determine lipid deposition and cardiac function in pressure overload/unload myocardium in rats through banding and debanding of the ascending aorta through small suprasternal incision.       Methods      Forty-five 5-week-old male SD rats were randomly divided into sham operation group (control group

in 9

12 and 15 weeks after small suprasternal incision respectively as C1

C2 and C3 groups)

ascending aortic banding groups (banding for 9

12 and 15 weeks respectively as A1

A2 and A3 groups)

and ascending aortic banding groups (debanding for 0

3 and 6 weeks respectively after 9 weeks’ banding as B1

B2 and B3 groups)

and there were 5 animals in each group. Animal ultrasonography was used to evaluate the cardiac function in each group. The expression of Kruppel-like factor 15 (KLF15) at mRNA and protein levels was detected by PCR and Western blotting respectively. Lipid staining was employed to measure the lipid deposition in the myocardium during pressure overload/unload.       Results      Compared with the control group

the cardiac function was decreased with the increase of banding time

and the ejection fraction (EF%) was significantly lower in the A1

A2 and A3 groups than the C1

C2 and C3 groups (54.32±3.88 vs 85.32±3.90

47.91±3.64 vs 85.45±4.26

40.08±4.45 vs 82.83±4.93

P0.01)

and it was also decreased in the B1

B2 and B3 groups (53.78±3.58

63.28±5.81 and 63.59±6.48

P0.05). Compared to the A1 group

the EF% was significant increased in the B2 and B3 (both P0.05). The mRNA and protein levels of KLF15 were significant decreased in the A1

B2 and B3 groups than the C1

C2 and C3 groups (mRNA: 0.66±0.09 vs 1.76±0.07

0.52±0.07 vs 1.78±0.12

0.51±0.04 vs 1.70±0.13; Protein: 0.99±0.05 vs 1.25±0.04

0.96±0.05 vs 1.30±0.09

1.01±0.08 vs 1.30±0.06

all P0.01). But there were no statistical differences in the levels in the A1 group with the B2 and B3 groups. Myocardial lipid deposition was higher in the A1

B2 and B3 groups than the C1

C2 and C3 groups

and its was decreased in the B2 and B3 than the A1 group

but still higher than the control group.       Conclusion      During cardiac pressure overload/unload

KLF15 may play negative regulative role in the lipid deposition in the heart

and is involved in cardiac function recovery after unloading.