The effect of glucose on insulin release and ion movements in isolated pancreatic islets of rats in old age.

摘要

1. The effect of glucose on 86Rb+ efflux, 45Ca2+ net uptake and insulin secretion of pancreatic islets from 3- and 24-month-old rats was studied. 2. Raising the glucose concentration from 3 to 5.6 and 16.7 mM had no effect on 86Rb+ efflux from islets of 24-month-old male rats whereas that from 24-month-old female rats was decreased. 3. At 16.7 mM-glucose, net uptake of 45Ca2+ was significantly diminished in islets of 24-month-old rats compared to islets of 3-month-old rats. 4. In the presence of 16.7 mM-glucose, islets of 24-month-old rats exhibited only 60-70% of the insulin release obtained with islets from 3-month-old rats. 5. Neither net uptake of 45Ca2+ nor insulin secretion appear to differ between the sexes. 6. These data suggest that the decreased insulin secretory response to glucose during old age is due, at least in part, to inadequate inhibition of K+ efflux and diminished net uptake of Ca2+.