title: Plasma membrane vesicles from isolated hepatocytes retain the increase of amino acid transport induced by dibutyryl cyclic AMP in intact cells.
abstract: We have investigated the effect of cyclic AMP on hepatic amino acid transport by measuring the uptake of L-alanine in plasma membrane vesicles purified from hepatocytes incubated without or with dibutyryl cyclic AMP. The application of an Na+ gradient to vesicles from hepatocytes exposed to dibutyryl cyclic AMP, compared to control, resulted in a greater transient accumulation of L-alanine, whereas in the presence of a K+ gradient a similar slow equilibration of L-alanine was observed. Kinetic analysis of L-alanine influx revealed that the increased uptake resulted from an increased capacity (Vmax) with no change in the affinity (Km) of the carriers for L-alanine. These results strongly suggest that dibutyryl cyclic AMP induces stable changes at the membrane level probably by increasing the number of amino acid carrier molecules.
mesh_terms: D000409:Alanine / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D005934:Glucagon / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D018027:Receptors, Glucagon
chemical_list: D011956:Receptors, Cell Surface; D018027:Receptors, Glucagon; D003994:Bucladesine; D005934:Glucagon; D011972:Receptor, Insulin; D000409:Alanine