Provincial Clinical Medicine College of Fujian Medical University, No. 134 East Street, Gulou District, Fuzhou, Fujian, 350000, People's Republic of China.
Department of Cardiology, Fujian Provincial Hospital, No. 134 East Street, Gulou District, Fuzhou, Fujian, 350000, People's Republic of China.
Pharmacol Rep. 2020 Dec;72(6):1706-1716. doi: 10.1007/s43440-020-00094-2. Epub 2020 May 25.
In this study, we investigated the effect of forskolin (FSK, a selective adenylate cyclase agonist) on the automatic diastolic depolarization of sinus node cells (SNC) with hypoxia/reoxygenation (H/R) injury.
The SNC of the newborn rat was randomly assigned into the control group, the H/R (H/R injury) group, or the H/R + FSK (H/R injury + FSK treatment) group. Patch-clamp was performed to record the action potential and electrophysiological changes. The cellular distribution of intracellular calcium concentration was analyzed by fluorescence staining.
Compared with the control cells, spontaneous pulsation frequency (SPF) and diastolic depolarization rate (DDR) of H/R cells were reduced from 244.3 ± 10.6 times/min and 108.7 ± 7.8 mV/s to 130.5 ± 7.6 times/min and 53.4 ± 6.5 mV/s, respectively. FSK significantly increased SPF and DDR of H/R cells to 208.3 ± 8.3 times/min and 93.2 ± 8.9 mV/s (n = 15, both p < 0.01), respectively. H/R reduced the current densities of I, I and inward I, which were significantly increased by 10 μM FSK treatment (n = 15, p < 0.01). Furthermore, reduced expression of HCN4 and NCX1.1 channel protein were significantly increased by FSK. Inhibitor studies showed that both SQ22536 (a selective adenylate cyclase inhibitor) and H89 (a selective protein kinases A [PKA] inhibitor) blocked the effects of FSK on SPF and DDR.
H/R causes pacemaker dysfunction in newborn rat sinoatrial node cells leading to divergence of the DD and the slow of spontaneous APs, which change can be dramatically reversed by FSK through increasing I and I current in H/R injury.
在这项研究中，我们研究了 forskolin（FSK，一种选择性腺苷酸环化酶激动剂）对缺氧/复氧（H/R）损伤的窦房结细胞（SNC）自动舒张去极化的影响。
将新生大鼠的 SNC 随机分为对照组、H/R（H/R 损伤）组或 H/R+FSK（H/R 损伤+FSK 治疗）组。通过膜片钳技术记录动作电位和电生理变化。荧光染色分析细胞内钙离子浓度的细胞分布。
与对照组细胞相比，H/R 细胞的自发搏动频率（SPF）和舒张去极化率（DDR）从 244.3±10.6 次/分和 108.7±7.8 mV/s分别降至 130.5±7.6 次/分和 53.4±6.5 mV/s。FSK 显著增加了 H/R 细胞的 SPF 和 DDR，分别达到 208.3±8.3 次/分和 93.2±8.9 mV/s（n=15，均 p<0.01）。H/R 降低了 I、I 和内向 I 的电流密度，10 μM FSK 处理显著增加了这些电流密度（n=15，均 p<0.01）。此外，HCN4 和 NCX1.1 通道蛋白的表达减少，而 FSK 则显著增加了这些蛋白的表达。抑制剂研究表明，选择性腺苷酸环化酶抑制剂 SQ22536 和选择性蛋白激酶 A（PKA）抑制剂 H89 均阻断了 FSK 对 SPF 和 DDR 的作用。
H/R 导致新生大鼠窦房结细胞起搏功能障碍，导致 DD 发散和自发 APs 减慢，而 FSK 通过增加 H/R 损伤中的 I 和 I 电流，可显著逆转这些变化。
