IONIC BASIS FOR INTRACELLULAR C-14-NICOTINE ACCUMULATION IN SLICES FROM DIFFERENT RAT-BRAIN AREAS

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  • 1 January 1975
    • journal article
    • research article
    • Vol. 218  (2) , 252-267
Abstract
The effects of ionic alterations were studied on the accumulation, distribution and movements of 14C-nicotine in slices from rat brain striatum, hypothalamus, cortex and cerebellum. The uptake of 14C-nicotine 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. All 3 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 2-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. There may be an intracellular binding site for nicotine; the degree of binding is dependent upon the concentration of K+.