ABSTRACT
Aim To investigate the effects of lysophosphatidic acid on ischemia / reperfusion injury(IRI)and TRPV1 expression in isolated mouse heart.Methods The IRI model of isolated mouse heart was established by Langendorff device.The hearts in sham group were continuously perfused for 100 min.The hearts in IR group were stabilized for 10 min followed by no perfusion for 30 min and reperfusion for 60 min.Exogenous LPA was added in the K-H solution during IR in IR+LPA group while HA130, an LPA synthesis inhibitor, was intraperitoneally injected before IR in IR+HA130 group.The infarct volume was measured by TTC staining, the determination of LPA and LDH levels in coronary effluent and LPA concentration in serum was measured by ELISA method.Finally, the expression levels of pTRPV1/TRPV1 and Bcl-2/Bax in myocardial tissues were determined by Western blot.Results Compared with sham group, IR caused evident myocardial infarction and increased the levels of LDH and LPA in coronary effluent.The increase of LPA was linearly correlated with myocardial infarction volume.In addition, the protein levels of pTRPV1 and TRPV1 in myocardium increased, while the ratio of Bcl-2/Bax decreased.The myocardial injury in IR+LPA group was aggravated.In contrast, myocardial IRI was reversed in IR+HA130 group.Conclusions Myocardial ischemia-reperfusion induces the release of LPA, which aggravates myocardial post-ischemic injury, while the inhibition of LPA release exerts cardioprotective effects.The underlying mechanisms might be related to the regulation on cardiac TRPV1 expression and apoptotic signals.
ABSTRACT
Aim To observe the role of ERK signaling protein in morphine preconditioning reducing global ischemia-reperfusion injury in isolated rat hearts.Methods Adult male Sprague-Dawley rats were distributed into six groups (n =10 for each) using a random number table:control group (CON),ischemia-reperfusion group (I/R),ischemia preconditioning group (IPC),morphine preconditioning group at the concentration of 1 μmol · L-1 (MPC),ERK inhibitor PD98059 + MPC (MPD),and group of ERK inhibitor-PD98059 (PD).The isolated rat hearts were treated on a Langendorff perfusion apparatus system.The coronary effluent was collected at 15 min of equilibration (baseline),5 and 10 min of reperfusion for detection of the activity of LDH.Meanwhile,a water-filled balloon was inserted into the left ventricular for continuous LVDP measurement.The IS and AAR and IS/AAR ratios were observed by TTC.Western blot was used to examine the level of phosphorylated ERK in myocardium.Results As compared with the I/R group,MPC significantly decreased IS and IS/AAR ratio as well as LDH activities at 5 min and 10 min of reperfusion,but improved the LVDP at the end of reperfusion.Moreover,the phosphorylation level of ERK in myocardium was up-regulated by MPC.However,ERK inhibitor PD98059 could block the protective effects of MPC,as indicated by the increased IS and IS/AAR ratio,elevated LDH activity at the reperfusion of 5 and 10 min,and the suppressed LVDP at the end of reperfusion.Furthermore,the MPC-induced phosphorylation of ERK was also reversed by PD98059.Conclusion Morphine preconditioning may confer cardio-protection against the global ischemia-reperfusion injury in rat hearts through enhancing the phosphorylation of ERK.