The Effect Of Rapid Atrial Pacing-Induced Atrial Ultrastructure Changes In Rabbits

Atrial fibrillation (AF) is one of the common clinical arrhythmia, serious impact on human health and the quality of life, but its exact pathogenesis is not clear. Atrial fibrillation with atrial structural remodeling, electrophysiological remodeling and calcium ion distribution abnormality may lead to atrial generate multiple reentrant wave, and then promote the maintenance of atrial fibrillation.Therefore, this study was to observed the rapid atrial pacing structure change, provide new targets for further elucidation of the mechanisms of atrial remodeling in AF.Methods:Establishment of rapid atrial pacing in rabbits model, using RM6240physiological signal acquisition system, at the same time, stimulation and recording surface limb lead electrocardiography; atrial structural changes observed by light microscopy and electron microscopy, it is found that rapid pacing structure effects on atrial sarcoplasmic reticulum and mitochondria ultrastructure; on this basis, using Western blotting and spectrophotometric method was used to detect PO and P12expression and activity of the GRP78and mitochondrial mPTP opening, the mechanism of rapid atrial pacing induced changes in the atrial remodeling.Results: 1.the changes of atrial tissue structure, rapid atrial pacing at different moments of light microscopy and transmission electron microscopy results:1. HE staining, the atrial muscle fibers in a long strip shape, a branch, the branch is connected into a network. Nuclei were oval, located in the central atrium muscle fibers, muscle fibers visible light and dark stripes, and the control group (PO) and pacing at12hour (P12) had no obvious change between groups. Observation of transmission electron microscopy (P12) ultrastructure, visible dilatation of sarcoplasmic reticulum, mitochondria swelling, deformation, ridge arranged in disorder, disappear, massive vacuolization and glycogen accumulation was, myofilament dissolved, nuclear membrane rupture, depression, with the stimulation time of injury, P12more obvious. Therefore, this study selected PO and P12atrial tissue was studied2.Using Western blot and spectrophotometer to detect the change of GRP78and mitochondrial mPTP opening degree, results can be observed, GRP78increase in the P12atrial tissue, compared with PO up-regulated the expression of P12, the spectrophotometer combined determination of PO and P12in atrial tissue of mPTP opening degree swelling buffer induction method, in the induction of200umol/L Ca2+next, P12atrial muscle mitochondrial absorbance decreased rapidly, PO and P12respectively, suggesting that P12atrial muscle mitochondrial mPTP and PO were increased compared to open.Conclusion:1.Rapid pacing atrial dilatation of sarcoplasmic reticulum, endoplasmic reticulum stress marker protein, suggesting rapid pacing induced myocardial endoplasmic reticulum stress re distribution, and are involved in intracellular calcium.2.Rapid pacing myocardial mitochondria swelling, vacuolation, and lead to the changes of mitochondrial membrane potential, suggesting rapid pacing induced mitochondrial membrane structure and potential changes, leading to intracellular calcium redistribution...