Objective Observation of CT-1 C-terminal peptides in ischaemia -reperfusion injury before and after the intervention on myocardial cell apoptosis in SD rats.
Methods With ligation-release SD rats left posterior descending branch of coronary artery the ischaemia reperfusion heart model was established. 27 SD rats were randomly divided into four groups: Normal group (N, n=5); Disease group (D, n=6), Beginning of reperfusion after 30 min of MI; MI/R post-intervention group (T, n=8), Intraperitoneal injection of CT-1 C-terminal peptide (100 μg/kg) at same time of beginning of reperfusion after 30 min of MI; MI/R pre-intervention group (O, n=8), MI/R experiments was performed after intraperitoneal injection of CT-1C-terminal peptide (100 μg/kg) for 7 days. In accordance with the ECG monitoring results ended the experiment in animals dying, left the serum for examination of concentrations of CK and MDA and cut the ischaemic heart tissue and surrounding areas fixed in neutral solution of formaldehyde, paraffin-embedded and sliced. Using end-labelling TUNEL assay apoptosis of myocardial cells and calculate the cardiac myocyte apoptotic index (AI).
Results After MI/R, the average survival time of the disease group of SD rats was 93.17±24.7 min, that of MI/R pre-intervention group was 87.88±18.3 min. The average survival time of MI/R post-intervention group was 155.5±80.13 min, significantly longer than that of the disease and MI/R pre-(chronic) intervention group (p<0.01); The serum CK activity and MDA content and the myocardial apoptotic index (AI) around infarct area were increased significantly in disease group (N vs D, p<0.01), and which has been reduced significantly in the post-intervention group (T vs D, p<0.01). But still higher than that of normal group (q values were 5.197, 5.782, 7.391, respectively; p<0.01); The serum CK activity and MDA content were more higher in pre-ischaemia group than that in the disease group, and their apoptosis index (AI) is higher than that of normal group (p<0.01), but was no significant difference compared with the disease group (p>0.05); There were significant correlations between the myocardial apoptosis with myocardial injury and the extent of oxidative damage (r values were 0.9245, 0.8679, respectively; p<0.01).
Conclusion Short-term use of CT-1C-terminal peptide early in reperfusion can reduce myocardial tissue injury and oxidative damage, as well as the extent of cardiomyocyte apoptosis, so that the extension of animal survival time; but the intraperitoneal injection of CT-1C-terminal peptide after a longer period of time reduced the tolerance of SD rats on ischaemia reperfusion injury, the tissue injury and the extent of oxidative damage increased significantly, and cardiac myocyte apoptosis have occurred in the surrounding area of infarction, and the animals have a shorter survival time.