Effects of antiinsulin receptor antibodies on amino acid uptake by cultured rat hepatocytes.
The effects of two antiinsulin receptor antisera (AIRA) on alpha-amino-2-[14C]isobutyric acid [( 14C]AIB) uptake by and [125I]insulin binding to cultured rat hepatocytes were examined. Diluted 1:100, both antisera inhibited insulin binding by 75-80%, mainly by decreasing available high affinity insulin-binding sites. Diluted 1:500, they decreased insulin binding and high affinity binding sites by 35-40%. Neither antiserum had an effect on basal [14C]AIB uptake, but decreased insulin-stimulated AIB uptake by 83% (dilution, 1:100; 24-h incubation) and 25% (dilution, 1:500; 24-h incubation), respectively. Insulin stimulation of AIB uptake correlated positively (r = 0.96; P less than 0.01) with insulin binding to high affinity receptors on hepatocytes incubated with normal serum or AIRA. We conclude that: 1) insulin stimulation of amino acid uptake by hepatocytes was mediated through insulin receptors, especially high affinity binding sites, and was inhibited by AIRA in parallel with receptor blockade; and 2) AIRA had no insulin-like effect on basal amino acid uptake by hepatocytes.
D000596:Amino Acids / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology*; D007074:Immunoglobulin G; D007328:Insulin / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000276:immunology*
D000596:Amino Acids; D000621:Aminoisobutyric Acids; D007106:Immune Sera; D007074:Immunoglobulin G; D007328:Insulin; C100049:2-aminoisobutyric acid; D011972:Receptor, Insulin