https://doi.org/10.1007/s00392-025-02625-4
1Universitätsklinikum Düsseldorf Klinik für Kardiologie, Pneumologie und Angiologie Düsseldorf, Deutschland; 2Universitätsklinikum Düsseldorf Institut für Molekulare Medizin III Düsseldorf, Deutschland
Background: In Diabetes mellitus Typ 2 expression of glucose transporter (GLUT)4 declines. This is of great importance in ischemia as relevance of glucose metabolism increases. The langendorff perfused heart model is well established for ex-vivo ischemia and used Krebs Henseleit buffer is based on glucose only as energy supply. However, ex-vivo post-ischemic recovery and myocardial mitochondrial function have not been investigated in (diet induced obesity) DIO mice compared to normal chow conditions. The sphingolipid Shingosin-1-Phosphat was shown to be cardio-protective in ischemia and to increase GLUT4. Therefore, we investigated the potency to improve ex-vivo DIO infarction by long-term increase of S1P.
Methods: Mice were fed with a high-fat diet for 24 weeks. For the last 12 weeks, additional 4-deoxypyridxone was admitted via drinking water. Hearts were explanted and transferred to langendorff perfusion system. After 20 minutes of equilibration, 40 minutes of ischemia were induced followed by two hours of reperfusion. Infarct size and functional recovery measured in % from baseline for derivate pressure (dp), maximum contraction (dpmax), maximum relexation (dpmin), left ventricular systolic pressure (PES) and diastolic pressure (PED). PCR analysis for apoptosis markers and glycolysis as well as mitochondrial respiration measured by OROBOROS® respirometry were measured over time (baseline, equilibration, ischemia, 1-hour and 2-hour reperfusion).
Results: DIO mice showed increased infarct size (NCD 43.7±9.6 % vs. DIO 56.5±13.7 %, p=0.0498) and worse functional recovery compared to NCD mice (dp – 60 min Rec in % of BL NCD 59.2±20.6 % vs. DIO 34.0±12.1 %, p=0.0010; dpmin – 60 min Rec in % of BL NCD 57.5±21.6 % vs. DIO 35.3±12.4 %, p=0.0041 und dpmax – 60 min Rec in % of BL NCD 66.5±22.1 % vs. DIO 34.7±13.2, p=0.0002). As underlying mechanism, mitochondrial respirometry revealed worse (representatively maximum FCCP respiration equilibration: NCD 229.3±83.2 vs. DIO 111.5±22.3, p=0.0156; maximum FCCP respiration ischemia: NCD 204.5±51.9 vs. DIO 121.8±18.7, p=0.0083). This was in line with reduction of glycolysis markers (phosphofructokinase 2 equilibration: NCD 1.1±0.3 2^ΔΔCT vs. DIO 0.5±0.1 2^ΔΔCT, p=0.0063; phosphofructokinase 2 after ischemia: NCD 1.0±0.2 2^ΔΔCT vs. DIO 0.5±0.1 2^ΔΔCT, p=0.0003). DOP treatment over time improved post-ischemic recovery by reduction of infarct size (DIO+DOP 38.2± 11.2 %, p=0.0486) and improvement of functional recovery (dp 51.2± 13.06 %. p=0.0139; dpmin 49.7±11.0, p=0.0294; dpmax 56.8±12.2 %, p=0.0034). Moreover, mitochondrial respiration was optimized by DOP treatment. In line, apoptosis markers were reduced and glycolysis markers enhanced (FADD 1-hour reperfusion: DIO 0.9±0.3 2^ΔΔCT vs. DIO+DOP 0.5±0.2 2^ΔΔCT, p=0.0146; phosphofructokinase 2 equilibration: DIO 0.5±0.1 2^ΔΔCT vs. DIO+DOP 0.8±0.2 2^ΔΔCT, p=0.0449).
Conclusion: In this study, we could show that infarct size and functional recovery is worse in DIO mice compared to NCD after ex-vivo ischemia in the langendorff perfused heart system. This might be since glucose metabolism is reduced under diabetic conditions. In line, mitochondrial function was attenuated in ex-vivo DIO hearts before and after ischemia. S1P was able to improve glycolysis, mitochondrial function and post-ischemic recovery. This underlines a possible importance of S1P for improvement of cardiac metabolism in diabetes.