EFFECT OF PROTEIN-MALNUTRITION ON NEUTRAL AMINO-ACID-TRANSPORT BY RAT HEPATOCYTES DURING DEVELOPMENT

Hepatocytes from suckling rats whose mothers were fed a low-protein diet (9% protein) showed a lower capacity for Na+-dependent L-alanine uptake [due to a decrease in maximal uptake rate (V-max) of a low-affinity component of transport] and were not able to respond to insulin or glucagon, whereas those from suckling pups whose mothers were fed the control diet (17% protein) had already developed the ability to upregulate L-alanine transport after hormone treatment. When animals from low-protein-fed mothers were weaned onto a hypoprotein diet, the overall capacity for Na+-dependent L-alanine uptake (apparent-V-max) and its responsiveness to pancreatic hormones were restored. Hepatocytes from these animals showed a lower response to glucocorticoid treatment. Amino acid availability was dramatically decreased in suckling and weanling rats fed a low-protein diet; These results support the hypothesis that nutrient supply is an important factor in the proper development of hepatic transport functions during the suckling-weaning transition.