Aerobic Exercise Increases Expression Of Sur1 And Sur2a Subunits Of K-Atp-Channels In Murine Diabetic Ventricular Cardiomyocytes.

Diabetes mellitus (DM) is one of the most prevalent and rapidly increasing non-communicable chronic diseases around the world. It has been related to left ventricular disfunction, as well to its electric remodeling. Cellular and molecular underlying mechanisms remains unveiled, at least in part. Phenotypic consequences includes QT Interval prolongation, ventricular arrhytmia, and cardiac sudden death. KATP-channels are considered as couplers of metabolism to membrane electric behavior in ventricular cells. At early DM stages, reduction in KATP-channels expression has been claimed as one of the main cardiac dysfunction underlying mechanisms. Physical exercise (PE) is postulated as a preventive and therapeutic intervention for diabetic cardiomyopathy. PURPOSE: to explore aerobic PE effects on expression of KATP-channel sulphonylurea receptors (SURs) in diabetic cardiomyocites. METHODS: 3 weeks male Wistar rats were randomly asigned to four groups, control with (EC) and without exercise (NEC); diabetes with (ED) and without exercise (NED) groups (n = 5, each). IP streptozotocin at 100 mg/Kg dosis was used to induce DM. DM was considered when glycaemia was ≥250 mg/dl in tail blood. EC and ED performed exercise in a treadmill 5 min at a 15 m/min pace, followed by 20 min at 20 m/min, along 13 consecutive days. NEC and NED spent similar periods of time in a nonfuctioning treadmill. At the end of the program animals were eutanized and tissue samples were obtained from the ventricular apex. Subsecuently, Real Time Polymerase Chain Reaction (rtPCR) was used to SURs expression quantitation. RESULTS: significant differences were found for weight and glycaemia between NEC and EC when compared to NED as well as to ED (p = 0.05). Relative expression (mRNA SURx/β-actin genes) was higher in ED: for SUR1, ED vs. NED were 10.54 ± 3.53 vs 1.32 ± 0.38 (p = 0.007), as well when compared to NEC (1.29 ± 0.47, p = 0.01). Similarly, SUR2A expression was higher in ED than in NED; 10.68 ± 2.54/1.22 ± 0.45 (p = 0.002), and than in NEC (1.18 ± 0.33, p = 0.06). No differences were found in the expression of SUR2B. CONCLUSIONS: Aerobic PE increases SUR1 and SUR2A isoforms of the KATP-channels sulfonylurea receptors. This phenomenon could be related to cardioprotective effects of aerobic physical exercise in Diabetes Mellitus.