Abstract
We have recently reported that during infusion of commercially available [6-3H]glucose, a radioactive nonglucose contaminant may accumulate in plasma causing errors in the measurement of glucose turnover. To determine whether purification of this tracer by HPLC (high-performance liquid chromatography) before infusion would eliminate the contaminant in plasma and remove the underestimation of glucose turnover reported during hyperinsulinemia, four normal subjects each underwent two 5-h euglycemic clamps during infusion of insulin (1 mU · kg-1 · min-1). Glucose turnover was measured with either commercially available [6-3H]glucose or with HPLC-purified [6-3H]glucose. HPLC analysis of samples from the clamps done with commercially available [6-3H]glucose showed that 9.7% of the infused tracer and 26% of the 'plasma glucose 3H radioactivity' were contaminants. In contrast, no contaminant was observed in the plasma during infusion of HPLC-purified [6-3H]glucose. During the last hour of the clamp, mean glucose turnover using commercially available [6-3H]glucose was less (P < 0.01) than the mean glucose infusion rate (7.6 ± 0.3 vs. 10.5 ± 0.3 mg · kg-1 · min-1) yielding apparent 'negative' (P < 0.001) hepatic glucose release. In contrast, when HPLC-purified [6-3H]glucose was employed, glucose turnover equaled the glucose infusion rate (10.4 ± 0.09 vs. 10.2 ± 0.9 mg · kg-1 · min-1) and hepatic glucose release was no longer negative. We conclude that removal of a tritiated nonglucose contaminant in [6-3H]glucose by HPLC yields correct estimations of glucose turnover at steady state.
Original language | English (US) |
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Pages (from-to) | E228-E233 |
Journal | American Journal of Physiology - Endocrinology and Metabolism |
Volume | 258 |
Issue number | 1 21-1 |
DOIs | |
State | Published - 1990 |
Keywords
- contamination
- hyperinsulinemic clamp
- negative glucose production
- radioactive isotopes
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Physiology
- Physiology (medical)