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To investigate the changes of SK2 channel expression in sinoatrial node of the heart failure (HF) rats induced by volume-overload.
The volume-overload HF rats were induced by aortocaval fistula(ACF，n=7)，sham-operated rats were regarded as control group (SO, n=7), the SO rats were cut open the abdominal cavity and punctured abdominal aorta, but without making a fistula between abdominal aorta and inferior vena cava. The echocardiogram indexes such as 1eft ventricular end-systolic diameter (LVEDs),1eft ventricular end-diastolic diameter (LVEDd),1eft ventricular fraction shortening (LVFS),1eft ventricular end-systolic diameter (LVEDs) were measured at 8 week after operation, heart weight(HW)and body weight(BW)of each rat were measured to ratio HW and BW when the heart was took out, the above indexes were used to evaluate the heart structure and function. Then the sinoatrial node cells were isolated and collected to observe the expression of the SK2 channel protein by immunofluorescent staining. Meanwhile, sinoatrial node tissues of rats were isolated to determine the change of SK2 channel protein expression by Western blot.
The data of echocardiogram showed that the systolic and diastolic function in HF rats significantly declined (LVEDd：SO 5.91±0.36 vs HF 11.15±0.91，P<0.01；LVEDs：SO 2.89±0.28 vs HF 7.89±0.70，P<0.01；LVEF（%）：SO 87.10±1.63 vs HF 62.10±2.57，P<0.01；LVFS（%）：SO 51.27±2.03 vs HF 30.05±1.66，P<0.01), and the ratio of HW/BW significantly increased (SO 244.19±36.87 vs HF 593.21±28.72，P<0.01). The results of immunofluorescent staining indicated that the SK2 channels were located on membrane of single sinoatrial node cell. The results of Western blot demonstrated that the protein expression of SK2 downregulated significantly in sinoatrial node of HF rats compared with SO rats(0.22±0.10 vs 0.31±0.16，P<0.01)
The expression of SK2 channels protein was significantly downregulated in sinoatrial node of HF rats.