INSULIN-SECRETION FROM ISLETS OF GK RATS IS NOT IMPAIRED AFTER ENERGYGENERATING STEPS

Insulin secretory responses of intact and electrically permeabilised i slets of Goto-Kakizaki (GK) rats, a novel model of non-insulin depende nt diabetes mellitus, and Wistar (control) rats were compared to inves tigate the mechanism of the impairment of insulin secretion from pancr eatic islets of GK rats. Insulin secretion from intact islets in respo nse to glucose, glyceraldehyde, succinate monomethylester and tetramet hyl p-phenylenediamine, which reduces cytochrome c directly, was signi ficantly impaired in GK rats compared to control rats (P < 0.05, P < 0 .01, P < 0.05 and P < 0.05, respectively). However, Ca2+-induced insul in release from electrically permeabilised islets of GK rats was highe r than that of control rats. Moreover, insulin secretion from intact i slets in response to 50 mM KCl, which depolarises islet cells, was not impaired in GK rats. These results indicate that insulin secretion fr om islets of GK rats is not impaired after energy generating steps of metabolism.