Weiss C, Atlas D
Department of Biological Chemistry, Hebrew University of Jerusalem, Israel.
Brain Res. 1991 Mar 8;543(1):102-10. doi: 10.1016/0006-8993(91)91053-4.
Bradykinin (BK) induced [3H]norepinephrine [( 3H]NE) release and phosphatidylinositol turnover were investigated in PC12 cells. Induction of [3H]NE release by BK is mediated by activation of BK-B2-receptors, as determined using type specific BK receptor antagonists. BK induces [3H]NE release with a half maximal effective concentration of 30 +/- 0.5 nM, and reaches maximal net fractional release of 9.0 +/- 1% with 200 nM BK. The BK-induced release is Ca2+ dependent, reaching maximal release at 1.0 mM Ca2+, is pertussis toxin insensitive (1 microgram/ml), slightly increased by a dibutyryl cAMP (1 mM) and not affected by inhibitors of the cyclooxygenase or lipoxygenase pathways. Voltage-sensitive Ca2+ channel blockers, verapamil (10 microM), nifedipine (10 microM), and omega-conotoxin (CgTx 10 nM), do not block the BK-induced release. However, a considerable inhibitory effect was obtained by divalent cations Co2+ (ED50 = 0.2 mM) and Ni2+ (ED50(2)+ = 1 mM). These results indicate the involvement of a Ca2+ channel in the BK-mediated release which is different from the L- or N-type voltage sensitive calcium channels. Whereas [Ca2+]ex is essential for the BK-induction of catecholamine release, the rise in level of InsP's induced by BK in the presence or in the absence of [Ca2+]ex is similar up to concentration of 1 microM. This indicates that the rise in InsP's induced by BK is not sufficient to cause neurotransmitter release. Moreover, subsequent addition of Ca2+ to BK-stimulated cells in Ca(2+)-free medium yields no release. Hence, no activity triggered by BK alone could be further stimulated by Ca2+ for induction of release.(ABSTRACT TRUNCATED AT 250 WORDS)
在PC12细胞中研究了缓激肽（BK）诱导的[3H]去甲肾上腺素（[3H]NE）释放和磷脂酰肌醇周转率。使用类型特异性BK受体拮抗剂确定，BK诱导的[3H]NE释放是由BK - B2受体激活介导的。BK诱导[3H]NE释放的半数有效浓度为30±0.5 nM，200 nM BK时达到最大净分数释放9.0±1%。BK诱导的释放依赖于Ca2+，在1.0 mM Ca2+时达到最大释放，对百日咳毒素不敏感（1微克/毫升），二丁酰cAMP（1 mM）使其略有增加，且不受环氧化酶或脂氧合酶途径抑制剂的影响。电压敏感性Ca2+通道阻滞剂维拉帕米（10 microM）、硝苯地平（10 microM）和ω -芋螺毒素（CgTx 10 nM）不阻断BK诱导的释放。然而，二价阳离子Co2+（ED50 = 0.2 mM）和Ni2+（ED50 = 1 mM）具有显著的抑制作用。这些结果表明，BK介导的释放涉及一种不同于L型或N型电压敏感性钙通道的Ca2+通道。虽然细胞外Ca2+对于BK诱导儿茶酚胺释放至关重要，但在存在或不存在细胞外Ca2+的情况下，BK诱导的肌醇磷酸（InsP's）水平升高在浓度高达1 microM时相似。这表明BK诱导的InsP's升高不足以引起神经递质释放。此外，在无Ca2+培养基中向BK刺激的细胞中随后添加Ca2+不会产生释放。因此，单独由BK触发的活性不能被Ca2+进一步刺激以诱导释放。（摘要截短至250字）
