NORADRENALINE CONTRACTS ARTERIES BY ACTIVATING VOLTAGE-DEPENDENT CALCIUM CHANNELS
NORADRENALINE CONTRACTS ARTERIES BY ACTIVATING VOLTAGE-DEPENDENT CALCIUM CHANNELS
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DOI：
10.1038/336382a0
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发表时间：
1988-11-24
期刊：
影响因子：
64.8
通讯作者：
WORLEY, JF
中科院分区：
文献类型：
--
作者：
NELSON, MT;STANDEN, NB;WORLEY, JF
去甲肾上腺素(NA)调节动脉平滑肌张力，从而调节血管直径和血流量。NA通过引起钙离子通过细胞膜1-3而明显增加肌张力。目前已经提出了两种钙离子内流途径：电压激活的钙通道和电压不敏感的NA激活的钙通透通道1。尽管已经在动脉平滑肌4、5中发现了电压激活的钙通道，但NA激活的电压不敏感的钙通道还没有发现。我们在这里显示，兔肠系膜动脉的NA收缩随去极化而增加。这一增加与单个电压依赖性钙通道开放状态概率(P)的增加平行。去甲肾上腺素的作用可以通过NA激活电压依赖性钙通道来解释，而不是通过打开第二种类型的通道来解释。我们直接证明了N A增加了单个钙通道的开放几率。因此，在NA存在的情况下，通过电压依赖性钙通道的钙内流可以调节生理膜电位下的平滑肌张力。这些结果可能与高血压等病理生理状况有关。
Noradrenaline (NA) regulates arterial smooth muscle tone and hence blood vessel diameter and blood flow1. NA apparently increases tone by causing a calcium influx through the cell membrane1–3. Two calcium influx pathways have been proposed: voltage-activated calcium channels and NA-activated calcium-permeable channels that are voltage-insensitive1. Although voltage-activated calcium channels have been identified in arterial smooth muscle4, 5, voltage-insensitive calcium channels activated by NA have not. We show here that NA contractions of rabbit mesenteric arteries increase with depolarization. The increase parallels the elevation of open-state probability (P) of single, voltage-dependent calcium channels. The action of noradrenaline can be explained by NA-activating voltage-dependent calcium channels, rather than by opening a second type of channel. We show directly that N A increases the open-state probability of single calcium channels. Thus, in the presence of NA, calcium entry through voltage-dependent calcium channels can regulate smooth muscle tone at physiological membrane potentials. These results may have relevance to pathophysiological conditions such as hypertension.