Obesity is the major cause of alterations in insulin secretion and calcium fluxes by isolated islets from aged rats
1992
Machado, U.F. | Nogueira, C.R. | Carpinelli, A.R.
To investigate the alterations in insulin secretion induced by aging, 2-month-old, 12-month-old, and 12-month old lean rats (submitted to a caloric restriction during the last month that causes a weight loss of approximately 20%) were studied. As expected, glucose intolerance and increased insulin response were observed during IV-GTT in 12-month-old rats. These effects were, however, reversed by weight loss. Insulin secretion was investigated in isolated islets both during static incubation and perifusion. In 12-month-old rats insulin secretion and (45)Ca(2+) efflux were lower only in the second phase of the hormonal secretion, suggesting an involvement of voltage-sensitive calcium channels in these phenomena. Considering that in vivo and in vitro alterations were reversed after weight loss, it is possible to conclude that obesity is probably a major cause of impaired insulin secretion in 12-month-old albino rats. Since (14)C-glucose metabolism was not changed in islets from aged rats, the effect of obesity on insulin secretion is not due to altered glucose metabolism in pancreatic B-cells.
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