[Effect of folic acid on 35S-methionine transport in vitro]

The experiments were carried out with 4-week-old broiler birds given a ration that was balanced in terms of basic nutrients. Following decapitation inverted intestinal sacs were prepared from the proximal part of the jejunum the incubation of which lasted 40 min. To elucidate the effect of folic acid on the transport of 35S-methionine the acid was used in a conc. of 4 X 10(-6). Studied was also the effect of replacing the sodium ion (148 mEq/l) in the incubation solution with equivalent amount of the potassium ion, and the incorporation into the same solution of monoiodine-acetic acid (10(-3)M) as it affects the transmembrane transport of methionine. The flasks with the sacs of each group of birds contained 10microCi 35S-methionine each. The content of cyclic 3', 5'-adenosine-monophosphate (cAMP), the SH-groups, and the activity of alkaline phosphatase in the jejunal mucosa were determined. Results showed that folic acid at 4 X 10(-6)M stimulated dependably both the transport and the incorporation of 35S-methionine into the erythrocytes. These processes were inhibited when monoiodine-acetic acid at 10(-3)M was added to the incubation solution. Identic negative effect was produced also when K+ was used instead of Na+. Folic acid was said to raise the content of cAMP, SH-groups, and the activity of alkaline phosphatase in the jejunal mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)