[Protective effects of metallothionein induced by dexamethasone against ischemia/reperfusion injury of myocardium of isolated rat heart].
OBJECTIVE
To investigate the protective effects of metallothionein (MT) induced by dexamethasone (DEX) against ischemia/reperfusion (I/R) injury of myocardium of isolated rat heart.


METHODS
Thirty-two Sprague-Dawley (SD) rats were divided randomly into the DEX and control groups. In the former group, the rats were pretreated with DEX, and in latter group distilled water was given before their hearts were isolated for Langendorff perfusion and I/R. MT was assessed by Western blotting. The left ventricular developed pressure (LVDP), maximal change rate of intraventricular pressure rise/down (+/-dp/dt max), coronary artery flow (CF) and reperfusion arrhythmias were observed dynamically before ischemia and during 60-minute reperfusion following 30-minute ischemia, The hearts were perfused with triphenyltetrazolium (TTC) after 60-minute reperfusion. The myocardial infarct size was measured with Adobe Photoshop. The levels of MB isoenzyme of creatine kinase (CK-MB), malonaldehyde (MDA), total superoxide dismutase (T-SOD), CuZn-SOD, catalase (CAT), glutathione peroxidase (GSH-Px) and the activities of Na+-K+-ATPase, Ca2+-Mg2+-ATPase were detected.


RESULTS
Compared with control group, the expression of MT was significantly increased (3.085+/-1.065 vs. 1.028+/-0.016, P<0.05), the LVDP, +/-dp/dt max and CF were greatly improved (all P<0.05), the accumulated point of ventricular arrhythmia and the infarct size were significantly reduced in DEX group [(2.00+/-1.41) scores vs. (6.63+/-4.24) scores and (28.38+/-11.22)% vs. (47.39+/-8.30)%, respectively, both P<0.01]. The level of CK-MB was significantly lowered in the DEX group compared with control group [(8.69+/-4.16)U/g vs. (18.15+/-5.59) U/g, P<0.01], and myocardium MDA content was decreased (P<0.05). Moreover, the levels of T-SOD, CuZn-SOD, CAT, GSH-Px, and the activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase were significantly increased (P<0.05 or/and P<0.01) in DEX group.


CONCLUSIONS
DEX induces upregulation of MT, which attenuates I/R injury in rat heart.
Zhuang
Mei
M
Department of Cardiology, The Affiliated Hospital of Guiyang Medical College, Guiyang 550004, Guizhou, China. zhuangmei@sina.com
Fang
Ying
Y
Wu
Li-rong
LR
Lei
Da-wei
DW
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D005979:Glutathione Peroxidase / Q000378:metabolism; D008297:Male; D008668:Metallothionein / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D017923:Sodium-Hydrogen Exchangers; D003907:Dexamethasone; D008668:Metallothionein; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D017301:Ca(2+) Mg(2+)-ATPase