Comparison of the rapid insulin sensitivity test (RIST), the insulin tolerance test (ITT), and the hyperinsulinemic euglycemic clamp (HIEC) to measure insulin action in rats

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Date
2002-08-31
Authors
Reid, MAG
Latour, MG
Legare, DJ
Rong, N
Lautt, WW
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Abstract
The objective was to compare the ability of the rapid insulin sensitivity test (RIST), the hyperinsulinemic euglycemic clamp (HIEC), and the insulin tolerance test (ITT) to detect hepatic insulin sensitizing substance (HISS) dependent insulin action. HISS action was augmented by feeding and inhibited by fasting, blockade of hepatic nitric oxide synthase, or blockade of hepatic muscarinic cholinergic receptors. A significant correlation was found between the RIST index and ITT nadir (r(2) = 0.84), but not between the glucose infusion rate of the HIEC and RIST index. There was, however, a relationship between the RIST index and the initial response during the HIEC. Use of the HIEC resulted in HISS-dependent insulin resistance in both conscious and anesthetized animals. We concluded that since the RIST and ITT were comparable in quantifying both HISS-dependent and HISS-independent insulin action, the RIST was validated against this standard. The observation that the HIEC is capable of detecting HISS action in the first rising slope of the test but not at the end of the test and that HISS release is fully blocked after the conclusion of the HIEC raises concerns about the use of the commonly used HIEC.
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Keywords
HISS, insulin resistance, insulin sensitivity tests, CHOLINERGIC BLOCKADE, GLUCOSE, RESISTANCE, REPRODUCIBILITY, HUMANS, OSCILLATIONS, INDUCTION, ATROPINE
Citation
0008-4212; CAN J PHYSIOL PHARMACOL, AUG 2002, vol. 80, no. 8, p.811 to 818.