Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, Ohio.
Am J Physiol Cell Physiol. 2021 Jul 1;321(1):C158-C175. doi: 10.1152/ajpcell.00118.2021. Epub 2021 May 26.
In whole cell patch clamp recordings, it was discovered that normal human adrenal zona glomerulosa (AZG) cells express members of the three major families of K channels. Among these are a two-pore (K2P) leak-type and a G protein-coupled, inwardly rectifying (GIRK) channel, both inhibited by peptide hormones that stimulate aldosterone secretion. The K2P current displayed properties identifying it as TREK-1 (KCNK2). This outwardly rectifying current was activated by arachidonic acid and inhibited by angiotensin II (ANG II), adrenocorticotrophic hormone (ACTH), and forskolin. The activation and inhibition of TREK-1 was coupled to AZG cell hyperpolarization and depolarization, respectively. A second K2P channel, TASK-1 (KCNK3), was expressed at a lower density in AZG cells. Human AZG cells also express inwardly rectifying K current(s) (K) that include quasi-instantaneous and time-dependent components. This is the first report demonstrating the presence of K in whole cell recordings from AZG cells of any species. The time-dependent current was selectively inhibited by ANG II, and ACTH, identifying it as a G protein-coupled (GIRK) channel, most likely K3.4 (KCNJ5). The quasi-instantaneous K current was not inhibited by ANG II or ACTH and may be a separate non-GIRK current. Finally, AZG cells express a voltage-gated, rapidly inactivating K current whose properties identified as K1.4 (KCNA4), a conclusion confirmed by Northern blot. These findings demonstrate that human AZG cells express K2P and GIRK channels whose inhibition by ANG II and ACTH is likely coupled to depolarization-dependent secretion. They further demonstrate that human AZG K channels differ fundamentally from the widely adopted rodent models for human aldosterone secretion.
在全细胞膜片钳记录中，发现正常人类肾上腺球状带（AZG）细胞表达三大钾通道家族的成员。其中包括两种孔（K2P）渗漏型和一种 G 蛋白偶联的内向整流（GIRK）通道，这两种通道都被刺激醛固酮分泌的肽激素抑制。K2P 电流的特性表明它是 TREK-1（KCNK2）。这种外向整流电流被花生四烯酸激活，并被血管紧张素 II（ANG II）、促肾上腺皮质激素（ACTH）和 forskolin 抑制。TREK-1 的激活和抑制分别与 AZG 细胞超极化和去极化相关。第二种 K2P 通道，TASK-1（KCNK3），在 AZG 细胞中表达密度较低。人类 AZG 细胞还表达内向整流钾电流（K），包括准瞬时和时变成分。这是首次报道在任何物种的 AZG 细胞全细胞膜片钳记录中存在 K。时变电流被 ANG II 和 ACTH 选择性抑制，鉴定为 G 蛋白偶联（GIRK）通道，很可能是 K3.4（KCNJ5）。准瞬时 K 电流不受 ANG II 或 ACTH 抑制，可能是一种单独的非 GIRK 电流。最后，AZG 细胞表达一种电压门控、快速失活的 K 电流，其特性被鉴定为 K1.4（KCNA4），这一结论通过 Northern blot 得到证实。这些发现表明，人类 AZG 细胞表达 K2P 和 GIRK 通道，其被 ANG II 和 ACTH 抑制可能与去极化依赖性分泌相关。它们进一步表明，人类 AZG K 通道与广泛采用的啮齿动物模型在人类醛固酮分泌方面存在根本差异。
