GTP requirement for isoproterenol activation of calcium channels in vascular myocytes.
GTP requirement for isoproterenol activation of calcium channels in vascular myocytes.
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GTP 需要异丙肾上腺素激活血管肌细胞中的钙通道。
DOI：
10.1152/ajpheart.1995.269.1.h195
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Cox,RH
中科院分区：
文献类型：
--
作者：
Shi,QY;Cox,RH
在胶原酶和弹性酶处理的兔门静脉肌细胞中，研究了激活β -肾上腺素能受体通路对门静脉钙电流（ICa）的影响。在室温（20℃）下，使用全细胞，电压钳法，保持电位为-60 mV，用含有（mM） 100 CsCl， 20四乙基氯化铵，5 NaCl, 5 MgATP， 20 N-2-羟乙基哌嗪-N'-2-乙磺酸（HEPES）和10 1,2-二（2-氨基苯氧基）乙烷-N，N ‘，N’-四乙酸（BAPTA）的移液管溶液进行分析。将细胞与含有（mM） 140 NaCl、5 KCl、1 MgCl2、5 CaCl2、10 HEPES和10葡萄糖的溶液混合。在对照条件下，这些肌细胞中仅存在l型ICa，在+10 mV下平均为3.5 +/- 0.3 pA/pF。在移液液中加入0.1 mM鸟苷5′-三磷酸（GTP）， 1 μ m异丙肾上腺素（Iso）或福斯克林（Fsk）使ICa: Iso均匀提高45 +/- 5%，Fsk均匀提高88 +/- 11%。这种ICa的增加与激活或失活的电压依赖性的显着变化无关，但与ICa失活率的小幅增加有关。Fsk也与ICa激活率增加有关。1 μ m心得安预处理可阻断异位效应，暴露后心得安可逆转异位效应。ICa对10 microM Iso或Fsk的响应小于对1 microM的响应，一些细胞显示ICa的稳态降低。当后者发生时，可用性的电压依赖向左移动5 +/- 0.4 mV。（摘要删节250字）
The effects of activating the beta-adrenoceptor pathway on calcium current (ICa) in rabbit portal vein (PV) were studied in myocytes freshly isolated by collagenase and elastase treatment. ICa was measured at room temperature (20 degrees C) using whole cell, voltage-clamp methods from a holding potential of -60 mV in cells dialyzed with a pipette solution containing (mM) 100 CsCl, 20 tetraethylammonium chloride, 5 NaCl, 5 MgATP, 20 N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES), and 10 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). The cells were superfused with a solution containing (mM) 140 NaCl, 5 KCl, 1 MgCl2, 5 CaCl2, 10 HEPES, and 10 glucose. Only L-type ICa was present in these myocytes, averaging 3.5 +/- 0.3 pA/pF at +10 mV under control conditions. With 0.1 mM guanosine 5'-triphosphate (GTP) added to the pipette solution, 1 microM isoproterenol (Iso) or forskolin (Fsk) uniformly increased ICa: Iso by 45 +/- 5% and Fsk by 88 +/- 11%. This augmentation of ICa was not associated with significant changes in the voltage dependence of activation or inactivation but was associated with a small increase in the rate of inactivation of ICa. Fsk was also associated with an increased rate of ICa activation. The Iso effect was blocked by pretreatment with 1 microM propranolol and reversed by propranolol after Iso exposure. The ICa response to 10 microM Iso or Fsk was smaller than the response to 1 microM, with some cells showing a steady-state reduction in ICa. When the latter occurred, the voltage dependence of availability was shifted to the left by 5 +/- 0.4 mV.(ABSTRACT TRUNCATED AT 250 WORDS)