ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: Binding of 125I-insulin to primary cultures of differentiated mouse astrocytes was time-dependent, reaching equilibrium after 2 h at 22°C, with equilibrium binding corresponding to 20.79 fmol/mg of protein, representing ∼5,000 occupied binding sites/cell. The half-life of 125I-insulin dissociation at 22°C was 2 min, with an initial dissociation rate constant of 4.12 ± 10-2 s-1. Dissociation of bound 125I-insulin was not accelerated significantly in the presence of unlabeled insulin (16.7 μM). Porcine and desoctapeptide insulins competed for specific 125I-insulin binding in a dose-dependent manner, whereas growth hormone, glucagon, and somatostatin did not. For porcine insulin, Scatchard analysis suggested multiple-affinity binding sites (high-affinity Ka= 4.92 ± 108M-1; low-affinity Ka= 0.95 ± 107M-1). After incubation with insulin (0.5 μM) for 2 h at 37°C, increases above basal values of 254 ± 23 and 189 ± 34% for [3H]uridine uptake and incorporation, respectively, were observed. After incubation with insulin (0.5 μM) for 24 h at 37°C, there were increases of 145 ± 6% for [3H]thymidine uptake and 166 ± 11% for thymidine incorporation. Basal and stimulated undine and thymidine uptake and incorporation were inhibited by 50 μM dipyridamole. These studies confirm that mouse astrocytes in vitro possess specific insulin receptors and demonstrate an effect of insulin on pyrimidine nucleoside uptake and incorporation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1987.tb10023.x
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