Huang H Y, Zhou C W
Shanghai Institute of Physiology, Chinese Academy of Sciences, China.
Zhongguo Yao Li Xue Bao. 1996 Jul;17(4):302-5.
To study the mechanism for 3, 4-diaminopyridine (DAP) evoking external Ca(2+)-independent release of [3H] norepinephrine ([3H] NE).
Rat hippocampal slices were preincubated with [3H] NE and superfused with medium. [3H] NE release was determined.
Under Ca(2+)-free conditions, DAP evoked [3H] NE release. In rats pretreated by reserpine, the effect of DAP was no longer detectable. Ca2+ chelator BAPTA-AM potently inhibited DAP-evoked [3H] NE release. Desipramine 100-500 mumol.L-1 strongly induced [3H] NE release in a concentration-dependent manner, whereas caffeine 30-70 mmol.L-1 was slightly effective on [3H]NE release. The blocker of Ca(2+)-induced Ca2+ releasable stores, dantrolene sodium did not attenuate DAP-evoked [3H]NE release.
In the absence of extracellular Ca2+, DAP evokes exocytotic release of [3H]NE from synaptic vesicles through liberation of internal Ca2+ from inositol 1, 4, 5-trisphosphate-sensitive Ca2+ stores.
研究3,4 - 二氨基吡啶（DAP）引发[3H]去甲肾上腺素（[3H]NE）非依赖细胞外钙的释放机制。
将大鼠海马切片用[3H]NE预孵育，然后用培养基进行灌流。测定[3H]NE的释放情况。
在无钙条件下，DAP可引发[3H]NE的释放。在经利血平预处理的大鼠中，不再能检测到DAP的作用。钙离子螯合剂BAPTA - AM能有效抑制DAP引发的[3H]NE释放。100 - 500μmol·L-1的地昔帕明以浓度依赖的方式强烈诱导[3H]NE释放，而30 - 70mmol·L-1的咖啡因对[3H]NE释放的作用较弱。钙离子诱导的钙离子释放储存的阻滞剂丹曲林钠并未减弱DAP引发的[3H]NE释放。
在细胞外无钙离子的情况下，DAP通过从肌醇1,4,5 - 三磷酸敏感的钙离子储存中释放内部钙离子，引发突触小泡中[3H]NE的胞吐释放。
