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DIURNAL VARIATIONS IN INSULIN SECRETION AND K + PERMEABILITY IN ISOLATED RAT ISLETS
Author(s) -
Delattre E,
CipollaNeto J,
Boschero Ac
Publication year - 1999
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.1999.03073.x
Subject(s) - medicine , endocrinology , insulin , l glucose , basal (medicine) , secretion , chemistry , mole , pancreatic islets , carbohydrate metabolism , biology , islet
1. The effects of glucose on insulin secretion and 86 Rb efflux from isolated rat islets were studied at six different times during a 24‐h period (00.00, 04.00, 08.00, 12.00, 16.00 and 20.00 h). 2. In the absence of glucose and in the presence of substimulatory concentrations (2.8 mmol/L) of the sugar, insulin secretion did not vary with the time of day. At a glucose concentration of 5.6 mmol/L the stimulated insulin secretion was greater than basal levels only at 20.00 h. 3. At a higher sugar concentration (8.3 mmol/L) the increase in insulin secretion and the reduction in 86 Rb efflux rate were more marked during the dark period. No effect of the time of day on insulin secretion was observed at glucose concentrations above 8.3 mmol/L (except in 27.7 mmol/L). 4. The time of day appears to affect insulin secretion mainly at glucose concentrations close to physiological values (5.6–8.3 mmol/L). 5. This result agrees with the ability of physiological amounts of glucose to alter the 86 Rb‐permeability of pancreatic B cells at the same time intervals.