Modulation of outward potassium currents in aligned cultures of neonatal rat ventricular myocytes during phorbol ester-induced hypertrophy.
Modulation of outward potassium currents in aligned cultures of neonatal rat ventricular myocytes during phorbol ester-induced hypertrophy.
复制标题
在佛波酯诱导的肥大过程中新生大鼠心室肌细胞排列培养物中外向钾电流的调节。
DOI：
10.1006/jmcc.2001.1386
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发表时间：
2001
影响因子：
5
通讯作者：
Long,KJ
中科院分区：
文献类型：
--
作者：
Walsh,KB;Sweet,JK;Parks,GE;Long,KJ
蛋白激酶C刺激的佛波酯在体外应用于心肌细胞时可诱导强烈的肥大反应。这项研究的目的是确定这种体外肥大模型是否与电压门控K+通道表达的变化有关。取新生大鼠3~4天的心肌细胞，接种于胶原凝胶上培养。膜电流采用膜片钳全细胞排列技术，Kv1.4、Kv4.2和Kv2.1α亚基的表达水平通过Western印迹分析进行定量。电压阶跃为−30 mV时，对齐的心肌细胞的瞬时和持续外向钾电流均被激活。通宵接触佛波酯(PMA)导致心肌细胞大小增加55%，Ito峰值降低三倍。在对照组和PMA处理组的心肌细胞中，没有观察到激活和稳态失活所需的半最大电压的差异。相比之下，PMA处理导致ISUS的四乙基铵敏感成分(TEA-ISUS)增加了62%，并与电流衰减的缓慢成分的出现有关。肥大心肌细胞中Kv1.4和Kv4.2α亚基的表达水平显著降低，而Kv2.1α亚基的密度增加。PMA诱导的Kvα亚基的改变可通过抑制丝裂原活化蛋白激酶通路而部分被阻止。因此，PMA诱导的培养心肌细胞肥大与电压门控性K+通道表达的改变有关。
Protein kinase C-stimulating phorbol esters induce a strong hypertrophic response when applied in vitro to cardiac ventricular myocytes. The aim of this study was to determine if this in vitro model of hypertrophy is associated with changes in the expression of voltage-gated K+channels. Myocytes were isolated from 3–4-day-old neonatal rats and cultured on aligned collagen thin gels. Membrane currents were measured with the use of the whole-cell arrangement of the patch clamp technique and the expression levels of the Kv1.4, Kv4.2 and Kv2.1 α subunits quantified using Western blot analysis. Voltage steps positive to −30 mV resulted in the activation of both a transient (Ito) and a sustained (Isus) component of outward K+current in the aligned myocytes. Overnight exposure to phorbol 12-myristate 13-acetate (PMA) caused a 55% increase in myocyte size and a three-fold reduction in the peak amplitude of Ito. No differences in the half-maximal voltages required for activation and steady-state inactivation were observed between Itomeasured in control and PMA-treated myocytes. In contrast, PMA treatment resulted in a 62% increase in a tetraethylammonium-sensitive component of Isus(TEA-Isus) and was associated with the appearance of a slow component of current decay. Expression levels of the Kv1.4 and Kv4.2 α subunits were strongly depressed in the hypertrophic myocytes, while the density of the Kv2.1 α subunit was enhanced. PMA-induced changes in the Kv α subunits were partially prevented through inhibition of the mitogen-activated protein kinase (MAPK) pathway. Thus, PMA-induced hypertrophy of cultured ventricular myocytes is associated with an altered expression of voltage-gated K+channels.