Ionic basis for intracellular 14C-nicotine accumulation in slices from different rat brain areas.
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+.
D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D009538:Nicotine / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D013997:Time Factors
D009538:Nicotine; D012964:Sodium; D011188:Potassium