Choline metabolism in normal and choline-deficient rats of different ages

Abstract

The rates of synthesis and degradation (decay times) of lipid-bound, liver choline were studied in normal and choline-deficient rats with body weights in the 40–100 gm range. The rate of choline synthesis from l-methionine-CH 3-C 14 decreased exponentially as the body weight increased and was greater in the choline-deficient rat than in the normal rat of the same body weight. The decay time of liver choline was constant and identical for normal and choline-deficient animals; liver choline labeled by incorporation of l-methionine-CH 3-C 14 or choline-CH 3-C 14 decayed at the same rates. Concentrations of lipid-bound liver and kidney choline, expressed on the basis of unit body weight, were unchanged in choline-deficient rats and did not vary with change in body weight. The concentration of free choline in the liver was the same in normal male and female rats, but the females had a higher concentration of free choline in the kidneys than males; free choline concentrations in liver and kidney were decreased in choline-deficient animals. Thus the free choline present in liver and kidneys seems to be more directly concerned with choline deficiency than are the lipid-bound forms of choline.