Impaired insulin release in aging rats: metabolic and ionic events.

We investigated the effect of aging on glucose uptake, glucose-induced O2 consumption, glucose-induced 45Ca movements, and calmodulin content to elucidate age-related impairment of glucose-induced insulin release in pancreatic islets of Wistar rats. Intact pancreatic islets from old (24-month-old) rats showed impaired glucose-induced insulin release; glucose uptake and O2 consumption were lower in old than in young (2-month-old) or adult (12-month-old) rats. Moreover, 45Ca uptake and calmodulin content were decreased in pancreatic islets from older rats, which explained the impairment in glucose-induced insulin release in aging. No major differences between the 3 age groups in glucose-induced 45Ca efflux in pancreatic islets were observed.