Affiliation:
1. Division of Endocrinology, Department of Medicine, State University of New York, Health Science Center at Brooklyn Brooklyn, New York
Abstract
This study describes and characterizes a putative sulfonylurea receptor. The radioligand used was [3H]glipizide (9 Ci/mmol). The β-cell plasma membranes were derived from a transplantable rat insulinoma generated by subcutaneous injection of RINm5F cells and purified by ultracentrifugation on a 15–55% sucrose gradient. Specific binding of [3H]glipizide to purified β-cell plasma membranes was determined to be maximal at temperatures of 4–23°C, pH 7.3, and an incubation of 2 h. Scatchard analysis indicated a single binding site with Kd = 7 nM and sulfonylurea binding of 0.93 pmol/mg membrane protein. Displacement of [3H]glipizide from the purified β-cell plasma membranes by various sulfonylureas and their analogues correlated well with their known hypoglycemic and insulinreleasing activities. Various agents, including nutrients, agents affecting Ca2+ flux, gastrointestinal hormones, and pancreatic hormones, had no effect on [3H]glipizide binding to the β-cell plasma membranes. Putative sulfonylurea receptors on β-cell and brain cell plasma membranes have been reported by several groups of investigators. Sulfonylurea binding to the β-cell is hypothesized to close an ATP-sensitive K+ channel, which leads to depolarization of the membrane and activation of a voltage-dependent Ca2+ channel.
Publisher
American Diabetes Association
Subject
Advanced and Specialized Nursing,Endocrinology, Diabetes and Metabolism,Internal Medicine
Cited by
38 articles.
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