Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andres Bello, Santiago, Chile.
FASEB J. 2018 Apr;32(4):2137-2147. doi: 10.1096/fj.201700365RR. Epub 2018 Jan 5.
Na-Ca exchanger (NCX) contributes to control the intracellular free Ca concentration ([Ca]), but the functional activation of NCX reverse mode (NCXrm) in endothelial cells is controversial. We evaluated the participation of NCXrm-mediated Ca uptake in the endothelium-dependent vasodilation of rat isolated mesenteric arterial beds. In phenylephrine-contracted mesenteries, the acetylcholine (ACh)-induced vasodilation was abolished by treatment with the NCXrm blockers SEA0400, KB-R7943, or SN-6. Consistent with that, the ACh-induced hyperpolarization observed in primary cultures of mesenteric endothelial cells and in smooth muscle of isolated mesenteric resistance arteries was attenuated by KB-R7943 and SEA0400, respectively. In addition, both blockers abolished the NO production activated by ACh in intact mesenteric arteries. In contrast, the inhibition of NCXrm did not affect the vasodilator responses induced by the Ca ionophore, ionomycin, and the NO donor, S-nitroso- N-acetylpenicillamine. Furthermore, SEA0400, KB-R7943, and a small interference RNA directed against NCX1 blunted the increase in [Ca] induced by ACh or ATP in cultured endothelial cells. The analysis by proximity ligation assay showed that the NO-synthesizing enzyme, eNOS, and NCX1 were associated in endothelial cell caveolae of intact mesenteric resistance arteries. These results indicate that the activation of NCXrm has a central role in Ca-mediated vasodilation initiated by ACh in endothelial cells of resistance arteries.-Lillo, M. A., Gaete, P. S., Puebla, M., Ardiles, N. M., Poblete, I., Becerra, A., Simon, F., Figueroa, X. F. Critical contribution of Na-Ca exchanger to the Ca-mediated vasodilation activated in endothelial cells of resistance arteries.
钠钙交换器（NCX）有助于控制细胞内游离钙浓度([Ca])，但内皮细胞中 NCX 反向模式（NCXrm）的功能激活存在争议。我们评估了 NCXrm 介导的 Ca 摄取在大鼠分离肠系膜动脉床内皮依赖性血管舒张中的参与。在去甲肾上腺素收缩的肠系膜中，乙酰胆碱（ACh）诱导的血管舒张被 NCXrm 阻断剂 SEA0400、KB-R7943 或 SN-6 处理所消除。一致地，在肠系膜内皮细胞的原代培养物和分离的肠系膜阻力动脉的平滑肌中观察到的 ACh 诱导的超极化被 KB-R7943 和 SEA0400 分别减弱。此外，两种阻断剂均消除了 ACh 激活的完整肠系膜动脉中的 NO 产生。相比之下，NCXrm 的抑制作用并不影响钙载体离子霉素和 NO 供体 S-亚硝基-N-乙酰青霉胺诱导的血管舒张反应。此外，SEA0400、KB-R7943 和针对 NCX1 的小干扰 RNA 减弱了 ACh 或 ATP 诱导的培养内皮细胞中[Ca]的增加。邻近连接分析的分析表明，NO 合成酶，eNOS 和 NCX1 在完整肠系膜阻力动脉内皮细胞的 caveolae 中相关。这些结果表明，NCXrm 的激活在阻力动脉内皮细胞中由 ACh 引发的 Ca 介导的血管舒张中起核心作用。
