The Effect Of Dantrolene Pretreatment On Myocardium Ischemia Reperfusion Injury

ObjectiveTo investigate the effect of dantrolene pretreatment on myocardial ischemia-reperfusion and explore the possible mechanism of action. Hemodynamic, Lactate dehydrogenase(LDH) activity, myocardial infarct size, the activity of mitochondrial Na+,K+-ATPase and Ca2+-ATPase, mitochondrial swelling, SR/ER Ca2+-ATPase (SERCA) activities, Ca2+ uptake and Ca2+ release from ryanodine receptors (RyR) were observed.MethodsForty-eight Wistar rats were randomly divided into three groups of controls (CON, n=16), ischemia-reperfusion(IR, n=16) and dantrolene pretreatment (DAN, n=16). Isolated rat hearts were mounted on a Langendorff perfusion apparatus. CON, isolated rat hearts were perfused with Krebs-Henseleit (K-H) perfusion buffer for 120 min. IR, isolated rat hearts were perfused with K-H buffer and maintained for 30 min of heart working, ischemia for 30 min and reperfused for 60 min; to the DAN, dantrolene were added to the perfusion buffer at 5 min,10min and 20min of control perfusion by turns, making the final concentration to be 1μmol/l,3μmol/l,5μmol/l respectively, therefore the hearts were treated with this substances for 25 min period of working perfusion, then followed with 30 min global myocardial ischemia and then 60 min reperfusion.8 of each group were randomly selected to measure heart rate (HR),aortic flow (AF),coronary flow (CF) and cardiac output (CO) of the three groups at 10min,25min and 90min respectively, then measure the LDH activity and the myocardial infarct size. The others were used to isolate mitochondria with differential centrifugation, measuring their Na+,K+-ATPase and Ca2+-ATPase activity and mitochondrial swelling. Then the supernatant were used to separate sarcoplasmic reticulum(SR) vesicles by ultracentrifugation, measuring their Ca2+-ATPase (SERCA) activities,Ca2+ uptake and Ca2+ release from ryanodine receptors (RyR).Result1 At 5 min, there is no difference of hemodynamics in there groups. At 10 min and 20 min, the differences between three groups have no statistical significance. At 30 min, only the coronary flow (CF) of DAN slightly increased when compared with CON and IR (P<0.05).2 The LDH activity and the myocardial infarct size were reduced by 32.2% and 24.1% respectively(P<0.05).3 In IR, the mitochondrial Na+,K+-ATPase and Ca2+-ATPase activities decreased(P <0.05), but there were no significant differences between the CON and DAN.4 In DAN, the extent of mitochondrial swelling were increased in comparison to CON but decreased to IR.5 DAN RyR exhibited an increased rate and maximum of Ca2+ release in comparison to CON, while CON increased to IR(P<0.05).6 SR vesicles Ca2+ uptake and SERCA activities had no significant differences between IR and DAN but decreased to CON(P< 0.05).Conclusions1 Dantrolene pretreatment can change the hemodynamic slightly. When the final concentration of dantrolene is 5μmol/l, the CF increased. Therefore the heart blood-supply increased. It protects ischemia-reperfused myocardium.2 Dantrolene pretreatment can reduce the myocardial infarct size and the LDH release of myocardial cells. Consequently, Dantrolene pretreatment can protect ischemia-reperfused myocardium.3 Dantrolene pretreatment can protect the activity of mitochondrial Na+,K+-ATPase and Ca2+-ATPase and decrease the extent of mitochondrial swelling. So, it can attenuate the ischemia-reperfusion injury.4 Dantrolene pretreatment protects the heart against ischemia-reperfusion injury, inhibiting calcium release from RyR probably.