The binding and the total uptake of [3H]asialoorosomucoid was studied in normal rats, streptozotocindiabetic rats and insuliii-treated diabetic rats.1. The binding of [3H]asialoorosomucoi'd to normal rat hepatocytes gave a curvilinear plot when analysed by the Scatchard method, suggesting either two classes of independent receptor sites with different apparent association constants or a negative cooperativity in binding. The data, plotted according to the method of De Meyts and Roth showed a decrease of the affinity constant with respect to site occupancy.2. The Scatchard plot obtained for the [3H]asialoorosomucoid binding to streptozotocin-diabetic rat hepatocytes was curvilinear. According to the independent site model, the receptor number of each class was decreased, without any change of the apparent association constants. According to the model of De Meyts and Roth, no modification of the interaction factor and apparent affinity constants was observed, whilst the total number of receptor sites was decreased by half in streptozotocin-diabetic rats as compared with normal rats.3. Study of the total uptake of [3H]asialoorosomucoId by hepatocytes from each group of rats showed a decrease by half of the endocytosis in streptozotocin-diabetic rats as compared with normal rats.4. Insulin treatment of the streptozotocin-diabetic rats restored both parameters studied to normal level, whilst the withdrawal of insulin treatment decreased their level to that of streptozotocin-diabetic rats.These results are related to possible modifications of the hepatic binding protein, receptor for the plasma asialoglycoproteins, in the diabetic state.

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