Alderdice M T, Weiss G B
Arch Int Pharmacodyn Ther. 1975 Dec;218(2):252-67.
The effects of ionic alterations on the accumulation, distribution and movements of 14C-nicotine in slices from rat brain striatum, hypothalamus, cortex and cerebellum were studied. The uptake of 14C-nicotone is not dependent upon Na+ present in the incubation fluid because a K+-substituted (O-Na+) solution increased the 14C-nicotine tissue space, a tris-substituted (O-Na+) solution decreased the 14C-nicotine tissue space and a sucrose-substituted (O-Na+) solution did not change the amount of 14C-nicotine taken up when compared to the 14C-nicotine tissue space obtained in a normal incubation solution. However, all three Na+-free solutions elicited a sustained decrease in 14C-nicotine efflux. The increase in 14C-nicotine space produced in a K+-substituted (O-Na+) solution was present primarily in the slower component of a two-component washout, whereas the decrease produced in a tris-substituted (O-Na+) solution produced an equal percentage decrease in the size of both components. Most of the observed effects could be attributed to a linear relationship between the logarithm of the intracellular K+ concentration and the 14C-nicotine tissue space. In conclusion, it appears that there is an intracellular binding site for nicotine and that the degree of binding is dependent upon the concentration of K+.
研究了离子变化对大鼠脑纹状体、下丘脑、皮层和小脑切片中¹⁴C-尼古丁积累、分布和移动的影响。¹⁴C-尼古丁的摄取不依赖于孵育液中的Na⁺，因为用K⁺替代（无Na⁺）的溶液增加了¹⁴C-尼古丁组织间隙，用三羟甲基氨基甲烷替代（无Na⁺）的溶液减少了¹⁴C-尼古丁组织间隙，而用蔗糖替代（无Na⁺）的溶液与在正常孵育溶液中获得的¹⁴C-尼古丁组织间隙相比，并没有改变¹⁴C-尼古丁的摄取量。然而，所有三种无Na⁺溶液都引起了¹⁴C-尼古丁流出的持续减少。在K⁺替代（无Na⁺）溶液中产生的¹⁴C-尼古丁间隙增加主要存在于双组分洗脱的较慢组分中，而在三羟甲基氨基甲烷替代（无Na⁺）溶液中产生的减少则使两个组分的大小都减少了相同的百分比。观察到的大多数效应可归因于细胞内K⁺浓度的对数与¹⁴C-尼古丁组织间隙之间的线性关系。总之，似乎存在尼古丁的细胞内结合位点，且结合程度取决于K⁺的浓度。
