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RECEPTOR‐MEDIATED 125 I‐LABELLED INSULIN DEGRADATION IN THE RAT HEPATOCYTE. STUDIES USING CHLOROQUINE
Author(s) -
Bonser Anne M,
Garciawebb Peter,
Bhagat Chotoo I
Publication year - 1983
Publication title -
australian journal of experimental biology and medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0004-945X
DOI - 10.1038/icb.1983.54
Subject(s) - chloroquine , insulin , hepatocyte , incubation , receptor , degradation (telecommunications) , internalization , insulin receptor , intracellular , chemistry , endocrinology , biology , medicine , biochemistry , in vitro , immunology , telecommunications , insulin resistance , malaria , computer science
Summary Degradation of insulin during incubation with target cells occurs via receptor‐mediated processes. In this study, receptor‐mediated degradation of 125 I‐labelled insulin was investigated in rat hepatocytes, using the agent chloroquine. Chloroquine increased specific cell‐associated 125 I‐labelled insulin at 37°. The increased radioactivity with chloroquine was intracellular (53.3 ± 1.2% of initially bound label was displaced by excess cold insulin; in control cells 67.0±2.1 % was displaced. P<0.005). The effect of chloroquine was prevented by adding label at 15° or by pre‐treatment with 5 mM KCN, 5 mM NaN 3 or 1 g/1 bacitracin, which indicated a post‐internalization site of action. Chloroquine had no effect on degradation of 125 I‐labelled insulin in buffer alone or in buffer previously incubated with cells. Specific studies of receptor‐mediated degradation at 37° showed that more 125 I‐labelled insulin remained associated with hepatocytes when chloroquine was present (P<0.0005 after 60 min). Analysis of chloroquine's effect on the intactness of 125 I‐labelled insulin released during processing of surface‐bound label at 37° showed that chloroquine‐sensitive mechanisms accounted for at least 50% of receptor‐mediated insulin degradation in rat hepatocytes.