Inhibitory effects of opioids on voltage-dependent Ca2+ channels and catecholamine secretion in cultured porcine adrenal chromaffin cells
Inhibitory effects of opioids on voltage-dependent Ca2+ channels and catecholamine secretion in cultured porcine adrenal chromaffin cells
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DOI：
10.1016/s0006-8993(02)02648-3
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发表时间：
2002-06-28
期刊：
影响因子：
2.9
通讯作者：
Ito, S
中科院分区：
文献类型：
--
作者：
Kitamura, G;Ohta, T;Ito, S
采用全细胞膜片钳技术研究阿片类药物对猪肾上腺嗜铬细胞电压依赖性钙通道（VDCCs）的抑制作用。用Fura-2微荧光法和电流法检测了阿片对高钾诱导的细胞内[Ca ~（2+）]_2升高和儿茶酚胺分泌的影响。从-80 mV的保持电位去极化至0 mV（测试脉冲）诱发内向钡电流（I-Ba），该电流可被甲硫氨酸脑啡肽可逆地抑制。甲硫氨酸-脑啡肽的这种抑制作用可被纳洛酮消除。阿片受体亚型的选择性激动剂（DAMGO：mu，DPDPE：8，U 50488：kappa）剂量依赖性地抑制I-Ba。在抑制效果上，DAMGO> U 50488>DPDPE。这些激动剂顺序应用在相同的细胞中产生可逆的I-Ba抑制。在ω-芋螺毒素GVIA存在下，DAMGO对I-Ba的抑制作用几乎消失，但ω-蛇毒毒素IVA加硝苯地平不存在。在测试脉冲之前施加调节预脉冲至+ 100 mV，部分恢复了DAMGO对I-Ba的抑制作用，表明阿片类药物诱导的VDCC抑制中涉及电压敏感成分。细胞内应用GDPbetaS或GTP-gammaS以及用百日咳毒素预处理显著降低了DAMGO诱导的I-Ba抑制的程度。DAMGO可逆性地抑制高K+引起的[Ca ~（2+）]_2升高和儿茶酚胺释放。RT-PCR显示μ-、δ-和K-阿片受体mRNA在培养的肾上腺嗜铬细胞中表达。这些结果表明，猪肾上腺嗜铬细胞具有μ-，δ-和κ-阿片受体和阿片受体的激活主要通过百日咳毒素敏感的G-蛋白抑制N-型VDCC。(C)2002 Elsevier Science B. V.保留所有权利。
The inhibitory effects of opioids on voltage-dependent calcium channels (VDCCs) were investigated in cultured porcine adrenal chromaffin cells using whole-cell patch clamp technique. The effects of the opioid on [Ca2+], increase and catecholamine secretion induced by high K+ were also examined in single cells by fura-2 micro fluorimetry and amperometry. A depolarizing pulse to 0 mV (test pulse) from a holding potential of -80 mV evoked an inward barium current (I-Ba), which was reversibly inhibited by methionine-enkephalin. This inhibitory effect of methionine-enkephalin was abolished by naloxone. Selective agonists of opioid receptor subtypes (DAMGO: mu, DPDPE: 8, U50488: kappa) dose-dependently inhibited I-Ba. In inhibitory potency, the order was DAMGO>U50488>DPDPE. These agonists applied sequentially produced a reversible I-Ba inhibition in the same cells. The inhibitory effect of DAMGO on I-Ba almost disappeared in the presence of omega-conotoxin GVIA but not omega-agatoxin IVA plus nifedipine. Application of a conditioning prepulse to + 100 mV prior to the test pulse partly retrieved the I-Ba inhibition by DAMGO, suggesting the involvement of voltage-sensitive components in opioid-induced VDCC inhibition. Intracellular application of GDPbetaS or GTP-gammaS as well as pretreatment with pertussis toxin significantly reduced the extent of I-Ba inhibition induced by DAMGO. DAMGO reversibly inhibited the [Ca2+], increase and catecholamine release induced by high K+. RT-PCR revealed the expression of mu-, delta- and K-Opioid receptor mRNAs in cultured adrenal chromaffin cells. These results suggest that porcine adrenal chromaffin cells possess mu-, delta- and kappa-opioid receptors and activation of Opioid receptors mainly inhibits N-type VDCCs via pertussis toxin-sensitive G-proteins. (C) 2002 Elsevier Science B.V. All rights reserved.