Mechanisms of accumulation of tyramine, metaraminol, and isoproterenol in isolated chromaffin granules and ghosts.
Mechanisms of accumulation of tyramine, metaraminol, and isoproterenol in isolated chromaffin granules and ghosts.
复制标题
酪胺、间氨醇和异丙肾上腺素在分离的嗜铬颗粒和鬼影中积累的机制。
DOI：
10.1016/0006-2952(82)90468-3
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发表时间：
1982
影响因子：
5.8
通讯作者：
Scarpa,A
中科院分区：
文献类型：
--
作者：
Johnson,RG;Carty,SE;Hayflick,S;Scarpa,A
用牛肾上腺嗜铬颗粒研究了跨膜pH梯度（Δ pH）和跨膜电位梯度（Δ Δ P）对几种拟交感神经胺摄取的影响。如前所述[R。约翰逊和A. Scarpa，J. biol. Chem. 254，3750（1979）]，新鲜分离的嗜铬颗粒保持颗粒内pH 5.5，如通过[14 C]甲胺分布测量的，并且在ATP存在下，产生80 mV的Δ，内部为正，如通过[14 C]硫氰酸盐分布测量的。当在pH 7.0下将三乙胺、间羟胺和异丙肾上腺素（1 - 50 mM）加入到缓冲良好的颗粒悬浮液中时，观察到颗粒内部的剂量相关性碱化。对放射化学标记的相同胺（5 - 21 μ M）的时间分辨流入的研究表明，所有胺都以明显的浓度梯度累积。然而，虽然[14 C] 5-羟色胺和[3 H]异丙肾上腺素的积累被利血平完全抑制，[14 C] tryramine的积累仅被抑制60%，[14 C]间羟胺的摄取不受影响。ATP依赖性的Δ β产生对胺摄取的刺激顺序为：5-羟色胺>异丙肾上腺素>酪胺;加入ATP不会增强间羟胺的蓄积。利用缺乏内源性基质梯度或成分的嗜铬鬼研究了每种拟交感神经胺的电化学质子梯度（Δ gm H+）和电化学梯度（Δ gm A）之间的关系。所有胺在单独存在Δ pH的情况下积累。在单独使用Δ β的情况下，[14-羟色胺]、[14-C]酪胺和[3-H]异丙肾上腺素蓄积，但未显示[3-H]间羟胺摄取。结果表明，5-羟色胺和异丙肾上腺素积累在孤立的嗜铬颗粒和鬼通过利血平敏感的机制，驱动的电化学质子梯度的大小。相反，间羟胺通过非极性脂质相渗透嗜铬颗粒的膜，并仅根据Δ pH分布。酪胺摄取通过两种机制进行。讨论了这些有效的生理和药理剂在体内作用的积累机制的影响。
The effects of the transmembrane pH gradient (ΔpH) and the transmembrane potential gradient (ΔΨ) on the uptake of several sympathomimetic amines were investigated, using bovine adrenal chromaffin granules isolated in isotonic sucrose. As previously described [R. Johnson and A. Scarpa, J. biol. Chem. 254, 3750 (1979)], freshly isolated chromaffin granules maintain an intragranular pH of 5.5 as measured by [14 C] methylamine distribution and, in the presence of ATP, generate a ΔΨ of 80 mV, positive inside, as measured by [14 C] thiocyanate distribution. When tryamine, metaraminol, and isoproterenol (1–50 mM) were added to well-buffered suspensions of granules at pH 7.0, a dose-related alkalinization of the granule interior was observed. Study of the time-resolved influx of the same amines labeled radiochemically (5–21 μM) revealed that all the amines were accumulated against an apparent concentration gradient. However, while accumulation of [14 C] serotonin and [3 H] isoproterenol was totally inhibited by reserpine,[14 C] tryramine accumulation was inhibited by only 60% and [14 C] metaraminol uptake was unaffected. The ATP-dependent generation of a ΔΨ produced a stimulation of amine uptake in the order: serotonin> isoproterenol> tyramine; metaraminol accumulation was not enhanced by ATP addition. The relationship between the electrochemical proton gradient (Δ\̄ gm H+) and the electrochemical gradient for each of the sympathomimetic amines (Δ\̄ gm A) was investigated utilizing chromaffin ghosts devoid of endogenous matrix gradients or components. All amines were accumulated in the presence of ΔpH alone. In the presence of ΔΨ alone,[14 serotonin,[14 C] tyramine, and [3 H] isoproterenol were accumulated, but no [3 H] metaraminol uptake was demonstrable. The results indicate that serotonin and isoproterenol accumulated in isolated chromaffin granules and ghosts via a reserpine-sensitive mechanism, driven by the magnitude of the electrochemical proton gradient. Conversely, metaraminol permeated the membrane of the chromaffin granule through the apolar lipid phase and distributed according to the ΔpH alone. Tyramine uptake proceeded by both mechanisms. The implications of the mechanism of accumulation of these potent physiologic and pharmacologie agents for their in vivo action are discussed.