[Activation of aldehyde dehydrogenase 2 attenuates myocardial injury in diabetic rats by regulating two-pore potassium channel TASK-1].

OBJECTIVE:To investigate the effect of activating aldehyde dehydrogenase 2 (ALDH2) on TASK-1 two-pore potassium channel in myocardial injury of diabetic rats.
 Methods: Diabetic rats were induced by intraperitoneal injection of streptozotocin (55 mg/kg). The diabetic rats were divided into 4 groups: normal group, diabetes at 4th week (DM4W) group, diabetes at 8th week (DM8W) group, and diabetes at 8th week+low concentration of ethanol intervention (DM8W+EtOH) group. The cardiac function of rats was determined by cardiac ultrasonography. The content of hydroxyproline was detected by ELISA. The appearance of myocardial morphous and positive material were observed by HE and PAS staining. The protein expression of TASK-1 was detected by Western blot. Whole-cell patch clamp technique was used to record the action potential duration at 30% and 90% repolarization (APD30, APD90) and two-pore potassium channel TASK-1 current in rat ventricular myocytes. Meanwhile, according to the sensitive electrophysiological characteristics of the potassium channel to acid and base, whether it is two-port potassium channel TASK-1current can be determined.
 Results: Compared with the N group, end-diastole left ventricular diameter (LVIDd), end-systolic left ventricular diameter (LVIDs), hydroxyproline content, TASK-1 protein expression increased, APD30 and APD90 extend, left ventricular fractional shortening (LVFS) and left ventricular ejection fraction (LVEF), and TASK-1 current decreased (all P<0.01) in the DM4W group and the DM8W group. HE staining showed that myocardial cell and fiber arrangement disorder, myocyte hypertrophy, myocardial widened and PAS staining reveals that positive material increased in the DM4W group and the DM8W group. Compared with the DM4W group, these changs are more obvious in DM8W rats (P<0.01 or P<0.05). Compared with the DM8W group, in the DM8W+EtOH group, the left ventricular function was restored, the hydroxyproline content and expression of TASK-1 protein were decreased, the TASK-1 current was increased, and APD30 and APD90 were shortened (all P<0.01). HE staining showed that myocardial cell injury was ameliorate and PAS staining showed decreased deposition of positive substances in the DM8W+EtOH group.
 Conclusion: Activation of aldehyde dehydrogenase 2 by low concentration of ethanol can reduce myocardial injury and fibrosis caused by diabetes, and its mechanism may be related to the changes of the two-por potassium channel TASK-1.

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