Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Roberto Alcântara Gomes Institute of Biology, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Cell Transplant. 2022 Jan-Dec;31:9636897221085883. doi: 10.1177/09636897221085883.
Acute kidney injury due to ischemia followed by reperfusion (IR) is a severe clinical condition with high death rates. IR affects the proximal tubule segments due to their predominantly oxidative metabolism and profoundly altered mitochondrial functions. We previously described the impact of IR on oxygen consumption, the generation of membrane potential (ΔΨ), and formation of reactive oxygen species, together with inflammatory and structural alterations. We also demonstrated the benefits of bone marrow mononuclear cells (BMMC) administration in these alterations. The objective of the present study has been to investigate the effect of IR and the influence of BMMC on the mechanisms of Ca handling in mitochondria of the proximal tubule cells. IR inhibited the rapid accumulation of Ca (Ca green fluorescence assays) and induced the opening of the cyclosporine A-sensitive permeability transition pore (PTP), alterations prevented by BMMC. IR accelerated Ca-induced decrease of ΔΨ (Safranin O fluorescence assays), as evidenced by decreased requirement for Ca load and for complete depolarization. Addition of BMMC and ADP recovered the normal depolarization profile, suggesting that stabilization of the adenine nucleotide translocase (ANT) in a conformation that inhibits PTP opening offers a partial defense mechanism against IR injury. Moreover, as ANT forms a complex with the voltage-dependent anion channel (VDAC) in the outer mitochondrial membrane, it is possible that this complex is also a target for IR injury-thus favoring Ca release, as well as the supramolecular structure that BMMC protects. These beneficial effects are accompanied by a stimulus of the citric acid cycle-which feed the mitochondrial complexes with the electrons removed from different substrates-as the result of accentuated stimulus of citrate synthase activity by BMMC.
缺血再灌注（IR）引起的急性肾损伤是一种严重的临床情况，死亡率很高。IR 影响近端肾小管节段，因为它们主要是氧化代谢，线粒体功能发生深刻改变。我们之前描述了 IR 对氧消耗、膜电位（ΔΨ）的产生以及活性氧的形成的影响，以及炎症和结构改变。我们还证明了骨髓单核细胞（BMMC）给药对这些改变的益处。本研究的目的是研究 IR 的影响以及 BMMC 对近端肾小管细胞线粒体钙处理机制的影响。IR 抑制了 Ca 的快速积累（Ca 绿色荧光测定），并诱导了环孢素 A 敏感的通透性转换孔（PTP）的开放，BMMC 可防止这些改变。IR 加速了 Ca 诱导的 ΔΨ下降（番红 O 荧光测定），这表现为 Ca 负载和完全去极化的需求减少。添加 BMMC 和 ADP 恢复了正常的去极化曲线，表明在抑制 PTP 开放的构象中稳定腺嘌呤核苷酸转运蛋白（ANT）提供了针对 IR 损伤的部分防御机制。此外，由于 ANT 在外膜线粒体中与电压依赖性阴离子通道（VDAC）形成复合物，因此该复合物也可能是 IR 损伤的靶标，从而有利于 Ca 释放以及 BMMC 保护的超分子结构。这些有益的影响伴随着柠檬酸循环的刺激 - 从不同底物中去除电子的复合物与线粒体复合物一起喂食 - 这是由于 BMMC 强烈刺激柠檬酸合酶活性的结果。
