The effect of age and glucose concentration on insulin secretion by the isolated perfused rat pancreas

Dariush Elahi, Denis C. Muller, Dana K. Andersen, Jordan D. Tobin, Reubin Andres

Research output: Contribution to journalArticle

Abstract

Age changes in the β-cell’s sensitivity to glucose as well as in its overall capacity to secrete insulin may play a part in the glucose intolerance of aging. The isolated perfused rat pancreas preparation was used to study the effect of age and glucose level on insulin secretion. Overnight-fasted male Wistar 12- and 23-month-old rats had basal plasma glucose levels of 106 ± 4 (SE) and 100 ± 4 mg/dl. Perfusate glucose levels were raised from 80 mg/dl to either 150, 220, or 360 mg/dl for 50 min (n = 6 to 8 in each group). Insulin secretion followed the typical biphasic pattern of an early spike and fall, followed by a sustained gradual increase at both ages. First-phase (0-10 min) insulin secretion in the old rats was significantly lower at 150 (184 vs. 524 µU/min, P < 0.05) and 220 mg/dl (327 vs. 644 min, P < 0.05), while it was nearly identical at 360 mg/dl. Although lower in the old rats, second-phase (11-50 min) insulin secretion was not statistically significantly different for each glucose level. When first- and second-phase insulin secretion rates were combined, the old rats’ insulin secretion was only lower at the 150 mg/dl level (248 vs. 426 µU/min, P < 0.05). Thus, at the more physiological glucose level, old rats showed a significantly lower response, while at the higher levels insulin secretion was similar. This diminishing age effect with increasing glucose dose suggests a defect in islet sensitivity to glucose rather than a diminished capacity to secrete insulin.

Original languageEnglish (US)
Pages (from-to)11-16
Number of pages6
JournalEndocrinology
Volume116
Issue number1
DOIs
StatePublished - Jan 1 1985

ASJC Scopus subject areas

  • Endocrinology

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