Trotta E E, Freire G L, Godinho C S
J Pharmacol Exp Ther. 1980 Sep;214(3):670-4.
Subcellular vesicles present in brain microsomal fraction take up calcium by an ATP-dependent process which is probably one of the mechanisms involved in the regulation of free calcium ions concentratioon in the cytosol of nerve cells. The experiments described in this paper were designed to test the effect of local anesthetics on this transport system since it is known that cytoplasmic calcium concentration interferes with nerve excitability and conduction and transmitter release. It was found that tetracaine increases the rate of calcium uptake in the range of 0.5 to 3 mM and inhibits calcium uptake in the range of 4 to 7 mM. Lidocaine and procaine increase calcium uptake in the range of 5 to 30 mM and inhibit calcium uptake in the range of 40 to 70 mM. The effects of local anesthetics were also tested on th ATP hydrolysis coupled with calcium uptake and on the ATP in equilibrium Pi exchange which represents the reverse reaction of this transport system. It was found that three local anesthetics inhibit ATP in equilibrium Pi exchange in concentrations which increase calcium uptake and inhibit ATP hydrolysis in concentrations which inhibit calcium uptake. These findings indicate that the enhancement of calcium uptake by the lower concentrations of local anesthetics is due to a decrease of the reverse reaction, whereas inhibition of calcium uptake by the higher concentrations of local anesthetics is due to the blockage of the transport adenosine triphosphatase.
脑微粒体组分中存在的亚细胞囊泡通过一种依赖ATP的过程摄取钙，这可能是参与调节神经细胞胞质溶胶中游离钙离子浓度的机制之一。本文所述的实验旨在测试局部麻醉剂对该转运系统的影响，因为已知细胞质钙浓度会干扰神经兴奋性、传导和递质释放。研究发现，丁卡因在0.5至3 mM范围内增加钙摄取率，而在4至7 mM范围内抑制钙摄取。利多卡因和普鲁卡因在5至30 mM范围内增加钙摄取，在40至70 mM范围内抑制钙摄取。还测试了局部麻醉剂对与钙摄取偶联的ATP水解以及对代表该转运系统逆反应的ATP与无机磷酸平衡交换的影响。结果发现，三种局部麻醉剂在增加钙摄取的浓度下抑制ATP与无机磷酸平衡交换，在抑制钙摄取的浓度下抑制ATP水解。这些发现表明，较低浓度局部麻醉剂增强钙摄取是由于逆反应减少，而较高浓度局部麻醉剂抑制钙摄取是由于转运三磷酸腺苷酶被阻断。
