Pascual R, Horga J F, Sánchez-García P, García A G
Naunyn Schmiedebergs Arch Pharmacol. 1977 Dec;301(1):57-64. doi: 10.1007/BF00501264.
The effects of ionophore X537A on the release of 3H-noradrenaline and its metabolites from the superfused guinea-pig left atrium were investigated. Concentrations of ionophore of 10 and 30 mocrometer greatly increased the release of tritium. Of the total increase in radioactivity elicited by X537A 44% was accounted for as noradrenaline and 50% was due to deaminated metabolites. The ionophore-evoked release of tritium was independent of the extracellular calcium ions and was not affected by agents which modify calcium movements such as verapamil, ryanodine, ruthenium red and tetracaine. X537A released 3H-noradrenaline from extragranular sites in MAO-inhibited atria from reserpine-treated animals and this release was also calcium independent. It is concluded that the ability of X537A to release noradrenaline from vesicular or cytoplasmic sites is not related to its ability to couple with and transport calcium ions through membranes. The ionophore might modify the ionic distribution outside and inside the neuronal membrane which would lead to leakage of the transmitter.
研究了离子载体X537A对豚鼠离体左心房释放³H-去甲肾上腺素及其代谢产物的影响。10和30微米浓度的离子载体极大地增加了氚的释放。由X537A引起的放射性总增加量中，44%为去甲肾上腺素，50%归因于脱氨基代谢产物。离子载体诱发的氚释放与细胞外钙离子无关，且不受维拉帕米、ryanodine、钌红和丁卡因等改变钙转运的药物影响。X537A从利血平处理动物的单胺氧化酶抑制心房的颗粒外部位释放³H-去甲肾上腺素，且这种释放也与钙无关。结论是，X537A从囊泡或细胞质部位释放去甲肾上腺素的能力与其通过膜结合和转运钙离子的能力无关。该离子载体可能会改变神经元膜内外的离子分布，从而导致递质泄漏。
