[Diabetes counteracts the protective effect of the diazoxide preconditioning on ischemic reperfused rat heart].
OBJECTIVE
To explore the impact of diabetic condition on the protective effect of diazoxide preconditioning (DPC) on ischemic-reperfused (I/R) myocardium in rats.


METHODS
Thirty normal male Sprague-Dawley rats were divided into 3 groups, including non-diabetic control group, non-diabetic I/R group, and non-diabetic I/R DPC group. Thirty diabetic male rats were also divided into the same 3 groups. The Langendorff isolated heart perfusion models were established. The control groups had a 90 min perfusion without any intervention. The I/R groups had a 30 min equilibration period, a 30 min ischemia, and a 30 min reperfusion. The I/R DPC groups had a 10 min equilibration, two cycles of 100 micromol/L diazoxide perfusion, 5 min each, followed by a 5 min diazoxide-free period before the 30 min ischemia and a 30 min reperfusion. The recovery rate of the left ventricular function, including cardiac output, left ventricular developed pressure (LVDP), and the maximum change rate of left ventricular pressure rise and fall (+/- dp/dt(max)) were recorded. The activity of creatine kinase in coronary outflow and activities of malonyldialdehyde, and superoxide dismutase in myocardium were detected. Myocardial water content was also assessed.


RESULTS
In non-diabetic rats, the content of creatine kinase, malonyldialdehyde and water content were significantly decreased in I/R DPC group compared with those in I/R group. Furthermore, in I/R DPC group, the activity of superoxide dismutase and the recovery rate of the left ventricular function, including cardiac output, LVDP and +/- dp/dt(max), were significantly increased compared with those in I/R group (P < 0.05). By contrast, there were no significant changes between I/R DPC group and I/R group in diabetic rats (P > 0.05).


CONCLUSIONS
Diabetes counteracts the protective effect of the diazoxide preconditioning on ischemic reperfused rat heart, which may be related with acute insulin resistance in cardiomyocytes.
Han
Jin-song
JS
Department of Cardiovascular Surgery, General Hospital of Shenyang Military Command, Shenyang 110016, China. hanjs0216@sina.com
Yan
De-min
DM
Zhu
Hong-yu
HY
Wang
Zeng-wei
ZW
D000818:Animals; D003921:Diabetes Mellitus, Experimental; D003981:Diazoxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016277:Ventricular Function, Left
D003981:Diazoxide