Secretory responses of intact glomus cells in thin slices of rat carotid body to hypoxia and tetraethylammonium
Secretory responses of intact glomus cells in thin slices of rat carotid body to hypoxia and tetraethylammonium
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DOI：
10.1073/pnas.030522297
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发表时间：
2000-02-29
影响因子：
11.1
通讯作者：
López-Barneo, J
中科院分区：
文献类型：
--
作者：
Pardal, R;Ludewig, U;López-Barneo, J
我们已经开发了一个薄片制备的整个大鼠颈动脉体，使我们能够进行膜片钳记录膜离子电流和监测儿茶酚胺分泌电流法在单个血管球细胞直接视觉控制下。在常氧条件下（PO 2约为140 mmHg; 1 mmHg = 133 Pa），大多数球细胞没有可测量的分泌活性，但暴露于缺氧（PO 2约为20 mmHg）引起了大量的尖峰样胞吐事件的出现。这种对缺氧的神经分泌反应是完全可逆的，需要细胞外Ca 2+内流。单量子事件的平均电荷为46 +/- 25 fC（n = 218），这产生了每个囊泡大约140，000个儿茶酚胺分子的估计。将四乙基铵（TEA; 2-5 mM）添加到细胞外溶液中在大多数（>95%）测试的细胞（n = 32）中诱导类似于由低PO 2引起的分泌反应。TEA也能刺激对低氧无反应但对高钾有激活作用的细胞。用伊比利亚毒素选择性阻断Ca ~（2+）和电压激活的maxi-K ~+通道后，也观察到类似于对低氧和TEA反应的分泌反应。我们的数据进一步表明，在颈动脉体的感觉转导膜离子通道是至关重要的。我们还表明，在完整的血管球细胞抑制电压依赖性K+通道可以有助于启动低PO 2的分泌反应。
We have developed a thin-slice preparation of whole rat carotid body that allows us to perform patch-clamp recording of membrane ionic currents and to monitor catecholamine secretion by amperometry in single glomus cells under direct visual control. In normoxic conditions (PO2 approximate to 140 mmHg; 1 mmHg = 133 Pa), most glomus cells did not have measurable secretory activity, but exposure to hypoxia (PO2 approximate to 20 mmHg) elicited the appearance of a large number of spike-like exocytotic events. This neurosecretory response to hypoxia was fully reversible and required extracellular Ca2+ influx. The average charge of single quantal events was 46 +/- 25 fC (n = 218), which yields an estimate of approximate to 140,000 catecholamine molecules per vesicle. Addition of tetraethylammonium (TEA; 2-5 mM) to the extracellular solution induced in most (>95%) cells tested (n = 32) a secretory response similar to that elicited by low PO2. tells nonresponsive to hypoxia but activated by exposure to high external K+ were also stimulated by TEA, A secretory response similar to the responses to hypoxia and TEA was also observed after treatment of the cells with iberiotoxin to block selectively Ca2+- and voltage-activated maxi-K+ channels. Our data further show that membrane ion channels are critically involved in sensory transduction in the carotid body. We also show that in intact glomus cells inhibition of voltage-dependent K+ channels can contribute to initiation of the secretory response to low PO2.