Laboratory of Experimental Intensive Care and Anaesthesiology, Department of Anaesthesiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands.
Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
Diabetologia. 2018 Mar;61(3):722-726. doi: 10.1007/s00125-017-4509-7. Epub 2017 Dec 2.
AIMS/HYPOTHESIS: Sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i) constitute a novel class of glucose-lowering (type 2) kidney-targeted agents. We recently reported that the SGLT2i empagliflozin (EMPA) reduced cardiac cytosolic Na ([Na]) and cytosolic Ca ([Ca]) concentrations through inhibition of Na/H exchanger (NHE). Here, we examine (1) whether the SGLT2i dapagliflozin (DAPA) and canagliflozin (CANA) also inhibit NHE and reduce [Na]; (2) a structural model for the interaction of SGLT2i to NHE; (3) to what extent SGLT2i affect the haemodynamic and metabolic performance of isolated hearts of healthy mice.
Cardiac NHE activity and [Na] in mouse cardiomyocytes were measured in the presence of clinically relevant concentrations of EMPA (1 μmol/l), DAPA (1 μmol/l), CANA (3 μmol/l) or vehicle. NHE docking simulation studies were applied to explore potential binding sites for SGTL2i. Constant-flow Langendorff-perfused mouse hearts were subjected to SGLT2i for 30 min, and cardiovascular function, O consumption and energetics (phosphocreatine (PCr)/ATP) were determined.
EMPA, DAPA and CANA inhibited NHE activity (measured through low pH recovery after NH pulse: EMPA 6.69 ± 0.09, DAPA 6.77 ± 0.12 and CANA 6.80 ± 0.18 vs vehicle 7.09 ± 0.09; p < 0.001 for all three comparisons) and reduced [Na] (in mmol/l: EMPA 10.0 ± 0.5, DAPA 10.7 ± 0.7 and CANA 11.0 ± 0.9 vs vehicle 12.7 ± 0.7; p < 0.001). Docking studies provided high binding affinity of all three SGLT2i with the extracellular Na-binding site of NHE. EMPA and CANA, but not DAPA, induced coronary vasodilation of the intact heart. PCr/ATP remained unaffected.
CONCLUSIONS/INTERPRETATION: EMPA, DAPA and CANA directly inhibit cardiac NHE flux and reduce [Na], possibly by binding with the Na-binding site of NHE-1. Furthermore, EMPA and CANA affect the healthy heart by inducing vasodilation. The [Na]-lowering class effect of SGLT2i is a potential approach to combat elevated [Na] that is known to occur in heart failure and diabetes.
目的/假设：钠-葡萄糖协同转运蛋白 2（SGLT2）抑制剂（SGLT2i）构成了一类新型的降低血糖（2 型）的肾脏靶向药物。我们最近报道，SGLT2i 依帕列净（EMPA）通过抑制钠/氢交换器（NHE）降低心肌细胞溶质 Na（[Na]）和细胞质 Ca（[Ca]）浓度。在这里，我们研究了（1）SGLT2i 达格列净（DAPA）和卡格列净（CANA）是否也抑制 NHE 并降低 [Na]；（2）SGLT2i 与 NHE 相互作用的结构模型；（3）SGLT2i 在多大程度上影响健康小鼠离体心脏的血液动力学和代谢性能。
在临床相关浓度的 EMPA（1 μmol/L）、DAPA（1 μmol/L）、CANA（3 μmol/L）或载体存在的情况下，测量了小鼠心肌细胞中的心肌 NHE 活性和 [Na]。应用 NHE 对接模拟研究探索 SGTL2i 的潜在结合位点。用恒流 Langendorff 灌流心脏进行 SGLT2i 处理 30 分钟，测定心血管功能、耗氧量和能量代谢（磷酸肌酸（PCr）/ATP）。
EMPA、DAPA 和 CANA 抑制 NHE 活性（通过 NH 脉冲后低 pH 恢复测量：EMPA 6.69±0.09、DAPA 6.77±0.12 和 CANA 6.80±0.18 与载体 7.09±0.09 相比；所有三种比较均 p<0.001）并降低 [Na]（mmol/L：EMPA 10.0±0.5、DAPA 10.7±0.7 和 CANA 11.0±0.9 与载体 12.7±0.7 相比；p<0.001）。对接研究提供了所有三种 SGLT2i 与 NHE 细胞外 Na 结合位点的高结合亲和力。EMPA 和 CANA 而非 DAPA 诱导完整心脏的冠状血管扩张。PCr/ATP 不受影响。
结论/解释：EMPA、DAPA 和 CANA 直接抑制心肌 NHE 流量并降低 [Na]，可能是通过与 NHE-1 的 Na 结合位点结合。此外，EMPA 和 CANA 通过诱导血管扩张来影响健康心脏。SGLT2i 的 [Na]降低类效应是一种对抗心力衰竭和糖尿病中已知发生的升高 [Na]的潜在方法。
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