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[ ABSTRACT] AIM:To investigate the effect of polysaccharide from Fructus corni ( PFC) on cardiomyocytes against hypoxia/reoxygenation ( H/R) injury and its possible relationship with ROS/PKC/p38 MAPK pathway.METHODS:Prima-ry cardiomyocytes were isolated from neonatal SD rats and randomly divided into normal group, H/R group, PFC (20 mg/L, 100 mg/L and 200 mg/L) preconditioning+H/R groups, chelerythrine+PFC (100 mg/L)+H/R group and SB203580+PFC (100 mg/L)+H/R group.The cell viability was measured by inverted microscopic observation.Apoptosis in the car-diomyocytes was detected by Hoechst 33258 staining and fluorescence microscopy.The levels of lactate dehydrogenase ( LDH) and superoxide dismutase ( SOD) in the cell culture supernatants, and the reactive oxygen species ( ROS) in the cells were also measured by microplate reader.The protein levels of PKC, p-p38 MAPK and HSP70 in the cells were detec-ted by Western blotting.RESULTS:Compared with normal group, the cell viability and beating frequency were decreased in H/R group.LDH and ROS contents, apoptotic rate and p-p38 MAPK level increased significantly (P<0.01).Compared with H/R group, PFC preconditioning increased beating frequency, SOD activity and the protein level of PKC and HSP70, and decreased ROS production, the protein level of p-p38 MAPK and cell apoptotic rate.However, the effect of PFC was in-hibited by chelerythrine or SB203580.CONCLUSION:PFC may protect cardiomyocytes from hypoxia/reoxygenation injury. Its mechanism is possibly involved in the inhibition of ROS via increasing the activity of SOD and the activation of PKC, and suppression of excessive activation of p38 MAPK.
ABSTRACT
Objective To evaluate the role of protein kinase C (PKC ) in reduction of mitochondrial injury during myocardial ischemia-reperfusion (I/R) by ischemic preconditioning in rats .Methods Forty male Sprague-Dawley rats ,aged 12-13 weeks ,weighing 280-320 g ,were randomly divided into 4 groups ( n=10 each) using a random number table:sham operation group (S group) ,I/R group ,ischemic preconditioning group (IP group) and PKC inhibitor chelerythrine group (C group) .Myocardial I/R was produced by 35 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion .Ischemic preconditioning was induced by 3 episodes of 5 min occlusion of left anterior descending branch at 5 min intervals before myocardial ischemia . Chelerythrine 1 mg/kg was injected intravenously via the caudal vein before ischemic preconditioning in group C . At 120 min of reperfusion ,the animals were sacrificed and the hearts were immediately removed .Mitochondrial suspension was prepared for determination of activities of succinate dehydrogenase (SDH ) , xanthine oxidase (XOD ) , glutathione peroxidase (GSH-Px ) and Ca2+-ATPase , content of Ca2+ , myocardial mitochonerial permeability transition pore (mPTP) opening and membrane potential (Δψm ) .Results Compared with S group , the activities of XOD and Ca2+-ATPase ,content of Ca2+ and mPTP opening were significantly increased ,and the activities of SDH and GSH-Px and Δψm were decreased in I/R group ( P<0.05) .Compared with I/R group ,the activities of XOD and Ca2+-ATPase , content of Ca2+ and mPTP opening were significantly decreased , and the activities of SDH and GSH-Px and Δψm were increased in IP group ( P<0.05) .Compared with IP group ,the activities of XOD and Ca2+-ATPase , content of Ca2+ and mPTP opening were significantly increased , and the activities of SDH and GSH-Px and Δψm were decreased in C group ( P<0.05) .Conclusion PKC is involved in reduction of mitochondrial injury during myocardial I/R by ischemic preconditioning in rats .