The pancreatic β-cell recognition of insulin secretagogues. II. Site of action of tolbutamide

Abstract

The distribution of 35S-labelled tolbutamide was studied in microdissected pancreatic islets of obese-hyperglycemic mice. These islets contain more than 90 % β-cells. A comparison with the uptake of 3H-labelled sucrose, mannitol, or 3-O-methyl-D-glucose revealed that tolbutamide did not enter the β-cells but was restricted to the extracellular space. It is suggested that the β-cell plasma membrane contains a tolbutamide receptor, which is responsible for the recognition of sulfonylureas as insulin secretagogues.