Effect of glibenclamide on the osmotic resistance of pancreatic β‐cells

Abstract

The effect of glibenclamide on the osmotic resistance of .beta.-cells was measured using isolated .beta.-cells from ob/ob-mice. The .beta.-cells were incubated at different osmolarity and the diameters of the approximately spherical .beta.-cells were measured at 22.degree. C or at 37.degree. C with the aid of a screw micrometer eyepiece fitted to a light microscope. A near linear decrease of .beta.-cell diameter was found with increasing osmolarity (111-617 mosm/l). Control experiments showed that the membrane stabilizers, imipramine (0.1 mmol/l) or tetracaine (1 mmol/l), strongly reduced the osmotic swelling induced by low osmolarity (180 mosm/l). Glibenclamide (0.001 or 0.2 mmol/l) did not affect the .beta.-cell diameter at normal osmolarity (317 mosm/l) but reduced the swelling induced by hypoosmolarity (180 mosm/l) and the shrinking induced by hyperosmolarity (617 mosm/l). Glibenclamide may increase the osmotic resistance of isolated .beta.-cells by changing transmembrane flow of ions.