Evidence for increased anionic arginase activity in pig enterocytes during development.

We have recently reported that the flux of L-arginine through arginase in enterocytes is increased in weaned pigs when compared with suckling animals (Blachier et al. 1993, Eur. J.

Metabolism of L-arginine through polyamine and nitric oxide synthase pathways in proliferative or differentiated human colon carcinoma cells.

HT-29 Glc-/+ cells originate from a human colon adenocarcinoma. These cells have been selected in a glucose-free culture medium and switched back in a glucose-containing medium. In this condition, they can spontaneously differentiate after confluency in enterocyte-like cells according to the activity of the brush-border associated hydrolase dipeptidyl peptidase IV.

Transglutaminase activity in enterocytes isolated from pig jejunum.

Polyamines appear to be involved in the turnover, growth and maintenance of intestinal mucosa integrity. Since polyamines could act -in part at least- through their incorporation into cellular proteins as catalyzed by transglutaminase, we have measured this enzyme activity in villus enterocytes isolated from pig jejunum and in homogenate derived from isolated cells. A part of putrescine, spermidine and spermine taken up by enterocytes is incorporated in TCA precipitable material derived from cells and this corresponds to the presence of transglutaminase activity in cellular homogenates.

Characterization and ontogenesis of nitric oxide synthase activity in pig enterocytes.

Nitric oxide has been implicated as a local modulator of several gastrointestinal functions. In this study, we have measured nitric oxide synthase activity in homogenates of enterocytes isolated from post-weaned pigs. The enzyme required the presence of NADPH and 6-(R,S)-5,6,7,8-tetrahydro-L-biopterin.

Intestinal arginine metabolism during development. Evidence for de novo synthesis of L-arginine in newborn pig enterocytes.

The capacity for L-arginine metabolism was studied in villus enterocytes isolated from pigs at birth, after 2-8 days suckling and after weaning. Immediately after birth, enterocytes were able to convert 1 mM L-citrulline, 2 mM L-glutamine or 1 mM L-ornithine to L-arginine. In 2-8-day-old animals, the net production of L-arginine from L-citrulline (2.

Polyamine metabolism in enterocytes isolated from newborn pigs.

In the pig, the growth of intestinal mucosa is very intense after birth. Since the polyamines are key elements affecting cell proliferation and differentiation, the present work was undertaken in order to know whether this hypertrophy is associated with an adaptation of polyamine metabolism. Villus enterocytes isolated from pig immediately after birth or 2 days later were found to contain similar amounts of putrescine, spermidine and spermine, i.

Stimulation by D-glucose of the direct conversion of arginine to citrulline in enterocytes isolated from pig jejunum.

In enterocytes isolated from pig jejunum, L-arginine is metabolized to L-citrulline either directly or indirectly through the sequence of reactions catalysed by arginase and ornithine transcarbamylase. In the presence of 5 mM D-glucose, the direct conversion of 1mM L-[guanido-14C] arginine to L-citrulline was increased more than 4 times. Isolated enterocytes exhibit a high glycolytic capacity.