Department of Physiology, School of Medical Sciences, Yanbian University, Yanji 133-002, China.
Cellular Function Research Center, Yanbian University, Yanji 133-002, China.
Oxid Med Cell Longev. 2022 Jun 20;2022:5905374. doi: 10.1155/2022/5905374. eCollection 2022.
Atrial natriuretic peptide (ANP), a canonical cardiac hormone, is mainly secreted from atrial myocytes and is involved in the regulation of body fluid, blood pressure homeostasis, and antioxidants. Cholecystokinin (CCK) is also found in cardiomyocytes as a novel cardiac hormone and induces multiple cardiovascular regulations. However, the direct role of CCK on the atrial mechanical dynamics and ANP secretion is unclear. The current study was to investigate the effect of CCK octapeptide (CCK-8) on the regulation of atrial dynamics and ANP secretion. Experiments were performed in isolated perfused beating rat atria. ANP was measured using radioimmunoassay. The levels of hydrogen peroxide (HO) and arachidonic acid (AA) were determined using ELISA Kits. The levels of relative proteins and mRNA were detected by Western blot and RT-qPCR. The results showed that sulfated CCK-8 (CCK-8s) rather than desulfated CCK-8 increased the levels of phosphorylated cytosolic phospholipase A2 and AA release through activation of CCK receptors. This led to the upregulation of NADPH oxidase 4 (NOX4) expression levels and HO production and played a negative inotropic effect on atrial mechanical dynamics via activation of ATP-sensitive potassium channels and large-conductance calcium-activated potassium channels. In addition, CCK-8s-induced NOX4 subsequently upregulated peroxisome proliferator-activated receptor (PPAR) coactivator-1 (PGC-1) expression levels through activation of p38 mitogen-activated protein kinase as well as the serine/threonine kinase signaling, ultimately promoting the secretion of ANP via activation of PPAR and PPAR. In the presence of the ANP receptor inhibitor, the CCK-8-induced increase of AA release, HO production, and the upregulation of NOX4 and CAT expressions was augmented but the SOD expression induced by CCK-8s was repealed. These findings indicate that CCK-8s promotes the secretion of ANP through activation of NOX4-PGC-1-PPAR/PPAR signaling, in which ANP is involved in resistance for NOX4 expression and ROS production and regulation of SOD expression.
心钠肽（ANP）是一种经典的心脏激素，主要由心房肌细胞分泌，参与体液调节、血压稳态和抗氧化作用。胆囊收缩素（CCK）也存在于心肌细胞中，作为一种新型的心脏激素，可诱导多种心血管调节。然而，CCK 对心房机械动力学和 ANP 分泌的直接作用尚不清楚。本研究旨在探讨 CCK 八肽（CCK-8）对心房动力学和 ANP 分泌的调节作用。实验在离体灌流跳动的大鼠心房上进行。采用放射免疫法测定 ANP。采用 ELISA 试剂盒测定过氧化氢（HO）和花生四烯酸（AA）的水平。通过 Western blot 和 RT-qPCR 检测相对蛋白和 mRNA 的水平。结果表明，硫酸化 CCK-8（CCK-8s）而非去硫酸化 CCK-8 通过激活 CCK 受体增加了细胞质磷脂酶 A2 的磷酸化水平和 AA 的释放。这导致 NADPH 氧化酶 4（NOX4）表达水平和 HO 产生上调，并通过激活三磷酸腺苷敏感性钾通道和大电导钙激活钾通道对心房机械动力学产生负性变力作用。此外，CCK-8s 诱导的 NOX4 通过激活丝裂原活化蛋白激酶 p38 以及丝氨酸/苏氨酸激酶信号通路，随后上调过氧化物酶体增殖物激活受体共激活因子-1（PGC-1）的表达水平，最终通过激活 PPAR 和 PPAR 促进 ANP 的分泌。在存在 ANP 受体抑制剂的情况下，CCK-8 诱导的 AA 释放、HO 产生增加以及 NOX4 和 CAT 表达上调增强，但 CCK-8s 诱导的 SOD 表达被逆转。这些发现表明，CCK-8s 通过激活 NOX4-PGC-1-PPAR/PPAR 信号通路促进 ANP 的分泌，其中 ANP 参与了对 NOX4 表达和 ROS 产生的抵抗以及 SOD 表达的调节。
