Objective To investigate the variation and significance of ERK1/2, Angiotensin II subtype 1 receptor (AT1R) and Angiotensin II subtype 2 receptor (AT2R) in hibernating myocardium.
Methods 6 little domestic Chinese pigs were implanted a constrictor into the right coronary artery through femoral artery to make a immediate 50%–75% stenosis in the target artery. 1 month later after the operation, NTG 99TCm-MIBI SPECT (single photon emission CT) was used to detect and locate hibernating myocardium before the animals were killed. Then verify the accuration of SPECT by observing the samples of hibernating myocardium (HM) under electron microscope. Finally assessing the variation of ERK1/2, p-ERK1/2 in normal myocardium and HM by western blot, AT1R and AT2R were localised by immunohistochemistry and quantified at protein level by western blot respectively.
Results 1. The spatial distribution of AT1R showed no difference among NM and HM. AT1R were found in myocytes and vascular smooth muscle cells (VSMCs); AT2R were found only in myocytes in NM, while in HM AT2R could be found not only in myocytes but also in VSMCs. 2. Compared with NM, the relative amount of AT1R significently reduced in HM while AT2R significently increased in HM. 3. p-ERK1/2 were significantly increased in HM compared with NM.
Conclusion The changes of AT1R and AT2R may help define the pathophysiological role of the angiotensin system in hibernatine myocardium.