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Comparison of the effect of GIP and GLP‐1 (7–36amide) on insulin release from rat pancreatic islets
Author(s) -
SIEGEL E. G.,
SCHULZE A.,
SCHMIDT W. E.,
CREUTZFELDT W.
Publication year - 1992
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1992.tb01820.x
Subject(s) - medicine , endocrinology , gastric inhibitory polypeptide , insulin , glucagon , glucagon like peptide 1 , islet , hormone , mole , chemistry , pancreatic hormone , pancreatic islets , biology , diabetes mellitus , type 2 diabetes , insulin resistance
. After ingestion of glucose both GIP (gastric inhibitory polypeptide, glucose‐dependent insulino‐tropic polypeptide) and GLP‐1 (7–36amide) (glucagon‐like polypeptide‐1, 7–36amide) may play a physiological role in augmenting insulin release. Their insulinotropic effect was compared in isolated rat islets after 24‐h maintenance in tissue culture (11 mmol l ‐1 glucose). Ten islets per vial were then incubated in Krebs‐Ringer‐Hepes buffer for 30 min; insulin was measured radioimmunologically. Both hormones were always compared in the same experiment. At 16.7 mmol l ‐1 glucose both GIP and GLP‐l(7–36amide) 2times10 ‐10 mol l ‐1 significantly increased insulin release; 10 ‐10 mol l ‐1 of either hormone had no significant effect. The response at 10 ‐9 and 10 ‐8 mol l ‐1 was similar for both; at 4times10 ‐10 mol l ‐1 GLP‐1(7–36amide), however, was clearly more effective than GIP. At low glucose (2.8 or 5.0 mol l ‐1 ) no sigificant differences were found. A concentration of 10 ‐8 mol l ‐1 of both hormones was slightly stimulatory. At 8.3 mmol l ‐1 glucose, 10 ‐9 mol l ‐1 GLP‐l(7–36amide) was 60% more effective than GIP (4.8 ± 0.4 vs. 3.0 + 0.4, n = 13, P <0.005), the response to 10 ‐8 mol l ‐1 was similar. These data show comparable effects of high concentrations of GIP and GLP‐1 (7–36amide) on glucose‐induced insulin release; at presumably physiological concentrations, however, GLP‐l(7–36amide) was clearly more effective. The combination of the two peptides was not more than additive, suggesting that they act via the same final mechanism.