The Role And Mechanism Of Danshensu Sodium In Preventing And Treating Ischemia-reperfusion Cardiac Dysfunction Based On Calcium Handling

ObjectiveCardiac function recovery is considered to be one of the indicators for assessing myocardium ischemia-reperfusion injury?MIRI?.Calcium overload caused by calcium mishandling in the myocardium is the"last common pathway"to cell damage.Salvia miltiorrhiza injection has been found to have anti-ischemic damage in the previous study.This thesis intends to explore the mechanism of Danshensu?DSS?,a major water soluble component of this injection,in preventing and treating ischemia-reperfusion cardiac dysfunction based on calcium handling.Methods1.The ischemia-reperfusion injury model?I/R?was constructed by langendorff perfusion technique and the effect of DSS on cardiac function in isolated I/R rats was observed.The hearts of SD rats were quickly separated and cardiac function indicators:heart rate?HR?,left ventricular systolic peak pressure?LVPSP?,left vent ricular end diastolic pressure?LVEDP?,time derivatives of pressure during contraction?+dp/dtmax?,time derivatives of pressure during relaxation?-dp/dtmax?were record.Coronary flow?CF?within any 2 min was collected before ischemia and after reperfusion,and the left ventricular development pressure?LVDP=LVPSP-LVEDP?was calculated.Myocardial ultrastructure effects were observated by transmission electron microscopy after 30 minutes after reperfusion.The SERCA2a protein activity in myocardial tissue of rats was observed by ELISA.The expressions of major calcium transporter?SERC A2a,NCX?and their regulative protein PLB,p-PLB?S16?,p-PLB?T17?,PKA in myocardial tissue were observed by western blot.2.Single ventricular myocytes were isolated by enzymatic decomposition,and electrical stimulation and caffeine-induced calcium transients was observed by laser confocal observation in myocytes.Results1.Danshensu improved contraction function of MIRI heart by increasing LVPSP?P<0.001?,LVEDP?P<0.001?,LVDP?P<0.001?,and reduced SR expansion.The activity and expression of SERCA2a protein?P<0.05?,which was decreased after MIRI,was restored by pretreatment of Danshensu.The increased?P<0.05?protein expression of T-PLB,p-PLB?T17?,and PKA after MIRI remained unchanged after the addition of Danshensu.In addition,p-PLB?S16?expression decreased after MIRI,which can be reversed?P<0.05?by addition of Danshensu.2.Calcium transients measured using fluorescence imaging revealed that decreased and slowed Ca²⁺released by Ry R2 and decreased calcium stores after ischemia-reperfusion were restored by pretreatment of Danshensu.Danshensu inhibited the reduction of Ca²⁺in the calcium pool,promoted the release of Ca²⁺by Ry R2,and increased the uptake of Ca²⁺by SERCA2a.ConclusionDuring ischemia-reperfusion injury DSS increased the activity and expression of SERC A2a and enhanced Ca²⁺uptake by increasing phosphorylation of p-PLB?S16?,which contribute to reducing calcium overload of cardiomyocytes a nd enhancing excitatory contraction coupling and improve cardiac function.