title: Comparative effects of native insulin and insulin-dextran complexes on the metabolism of adipose tissue.
abstract: Insulin-dextran complexes have been prepared and their biological activities compared to that of native insulin. Complexes referred to as T-70 had a molecular weight of about 450 000, T-2000 being more than 2 million. Insulin-dextran T-70 was stable and no release of free insulin from the complex was observed upon its incubation with adipose tissue. Insulin-dextran T-70 mimicked the effects of native insulin upon adipose tissue metabolism. It also lowered blood sugar. These effects necessitated, on an insulin molar basis, concentrations of the complex that were 10-times greater than those needed for native insulin. Maximal concentrations of insulin complex T-70 or native insulin elicited similar quantitative effects. This suggested that when the concentration of insulin-dextran T-70 was high enough, the complex occupied a sufficient number of receptor sites to produce maximal stimulation of the tissue. In contrast, insulin-dextran T-2000 was barely effective, indicating that, probably due to its size, it was unable to reach receptor sites. The size, stability and metabolic effects of insulin-dextran T-70 observed in this study give additional support to the concept that insulin action is probably mediated via a series of events initiated at the level of the plasma membrane of adipocytes.
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D003911:Dextrans / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D008053:Lipid Mobilization / Q000187:drug effects; D046911:Macromolecular Substances; D008297:Male; D051379:Mice; D008970:Molecular Weight; D011485:Protein Binding
chemical_list: D003911:Dextrans; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D046911:Macromolecular Substances; D005947:Glucose; D005990:Glycerol; D004837:Epinephrine