Adrenalectomy decreases amino-acid transport in hepatocytes

The effect of adrenalectomy on basal and hormone-stimulated amino-acid transport in liver was investigated by measuring the uptake of alpha-aminoisobutyric acid in freshly isolated rat hepatocytes. Adrenalectomy resulted in a 50% decrease in the transport capacity of hepatocytes; this change was accounted for by a diminution in the Vmax of a low affinity component of transport and specifically affected the A-transport system. Cortisone therapy fully restored the capacity of hepatocytes to transport amino acids. Sensitivity and responsiveness of hepatocytes from adrenalectomized animals to insulin, glucagon and dexamethasone, tested for the capacity of these hormones to stimulate AIB transport in vitro, were essentially identical with that of hepatocytes from control rats. The results support the concept of a positive (stimulatory) role of glucocorticoids in vivo, in the regulation of amino acid transport in the liver.