NA-DEPENDENT HIGH-AFFINITY UPTAKE OF CHOLINE INTO CULTURED FIBROBLASTS()

The acetylcholine precursor choline is transported into cholinergic ne urons by a high-affinity, sodium-dependent mechanism that is selective ly localized to the cholinergic nerve terminal. In addition, a low-aff inity, sodium-independent choline uptake system is present in choliner gic and non-cholinergic cells which deliver choline for cell membrane anabolism. Here, we show that uptake of [H-3]choline into cultured fib roblast cell lines exhibits high affinity (Km less-than-or-equal-to 10 muM), is sodium-dependent, and is blocked by hemicholinium, a classic al inhibitor of neuronal high-affinity choline uptake. Our data indica te that sodium-dependent high-affinity choline transport systems are a lso present in non-cholinergic cells. (C) 1994 Academic Press, Inc.