Department of Pharmacology and Toxicology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, P.O. Box 365067, San Juan 00936-5067, Puerto Rico.
Peptides. 2017 Oct;96:38-43. doi: 10.1016/j.peptides.2017.09.006. Epub 2017 Sep 7.
A growing body of evidence demonstrates an association between Angiotensin II (Ang II) receptor blockers (ARBs) and enhanced glucose metabolism during ischemic heart disease. Despite these encouraging results, the mechanisms responsible for these effects during ischemia remain poorly understood. In this study we investigated the influence of losartan, an AT1 receptor blocker, and secreted Ang II (sAng II) on glucose uptake and insulin receptor substrate (IRS-1) levels during cardiomyocyte swelling. H9c2 cells were differentiated to cardiac muscle and the levels of myogenin, Myosin Light Chain (MLC), and membrane AT1 receptors were measured using flow cytometry. Intracellular Ang II (iAng II) was overexpressed in differentiated cardiomyocytes and swelling was induced after incubation with hypotonic solution for 40min. Glucose uptake and IRS-1 levels were monitored by flow cytometry using 2-NBDG fluorescent glucose (10μM) or an anti-IRS-1 monoclonal antibody in the presence or absence of losartan (10M). Secreted Angiotensin II was quantified from the medium using a specific Ang II-EIA kit. To evaluate the relationship between sAng II and losartan effects on glucose uptake, transfected cells were pretreated with the drug for 24h and then exposed to hypotonic solution in the presence or absence of the secreted peptide. The results indicate that: (1) swelling of transfected cardiomyocytes decreased glucose uptake and induced the secretion of Ang II to the extracellular medium; (2) losartan antagonized the effects of swelling on glucose uptake and IRS-1 levels in transfected cardiomyocytes; (3) the effects of losartan on glucose uptake were observed during swelling only in the presence of sAng II in the culture medium. Our study demonstrates that both losartan and sAng II have essential roles in glucose metabolism during cardiomyocyte swelling.
越来越多的证据表明，血管紧张素 II（Ang II）受体阻滞剂（ARBs）与缺血性心脏病期间增强的葡萄糖代谢之间存在关联。尽管这些结果令人鼓舞，但在缺血期间负责这些影响的机制仍知之甚少。在这项研究中，我们研究了 losartan（一种 AT1 受体阻滞剂）和分泌的 Ang II（sAng II）在心肌细胞肿胀期间对葡萄糖摄取和胰岛素受体底物（IRS-1）水平的影响。使用流式细胞术测量分化的 H9c2 细胞中的肌球蛋白重链（Myosin Light Chain，MLC）和膜 AT1 受体的水平。在分化的心肌细胞中过表达细胞内 Ang II（iAng II），并用低渗溶液孵育 40min 后诱导肿胀。使用 2-NBDG 荧光葡萄糖（10μM）或抗 IRS-1 单克隆抗体通过流式细胞术监测葡萄糖摄取和 IRS-1 水平，在存在或不存在 losartan（10M）的情况下。使用特定的 Ang II-EIA 试剂盒从培养基中定量分泌的血管紧张素 II。为了评估 sAng II 与 losartan 对葡萄糖摄取的影响之间的关系，转染细胞用药物预处理 24h，然后在存在或不存在分泌肽的情况下暴露于低渗溶液中。结果表明：（1）转染的心肌细胞肿胀减少了葡萄糖摄取并诱导 Ang II 分泌到细胞外介质中；（2）losartan 拮抗了肿胀对转染心肌细胞中葡萄糖摄取和 IRS-1 水平的影响；（3）仅在培养基中存在 sAng II 的情况下，losartan 对葡萄糖摄取的影响才会在肿胀期间观察到。我们的研究表明，losartan 和 sAng II 在心肌细胞肿胀期间的葡萄糖代谢中都具有重要作用。
