Underestimation of glucose turnover corrected with high-performance liquid chromatography purification of [6-3H]glucose
Schwenk, W.F.; Butler, P.C.; Haymond, M.W.; Rizza, R.A.
American Journal of Physiology 258(1 Pt 1): E228-E233
1990
ISSN/ISBN: 0002-9513 PMID: 2405700 Document Number: 351486
During infusion of commercially available [6-superscript 3H]glucose, a radioactive non-glucose contaminant may accumulate in plasma causing errors in the estimation 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 hyperinsulinaemia, 4 normal persons each had 2 euglycaemic clamps of 5 h during infusion of insulin 1 mU/kg min. Glucose turnover was estimated with commercially available [6-superscript 3H]glucose or with HPLC-purified [6-superscript 3H]glucose. HPLC analysis of samples from the clamps done with commercially available [6-superscript 3H]glucose showed that 9.7% of the infused tracer and 26% of the "plasma glucose superscript 3H radioactivity" were contaminants. In contrast, no contaminant was observed in the plasma during infusion of HPLC-purified [6-superscript 3H]glucose. During the last hour of the clamp, mean glucose turnover using commercially available [6-superscript 3H]glucose was less than the mean glucose infusion rate (7.6 +or- 0.3 compared with 10.5 +or- 0.3 mg/kg min) yielding apparent "negative" hepatic glucose release. When HPLC-purified [6-superscript 3H]glucose was employed, glucose turnover was similar to the glucose infusion rate (10.4 +or- 0.9 compared with 10.2 +or- 0.9 mg/kg min) and hepatic glucose release was no longer negative.