In:
American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 256, No. 5 ( 1989-05-01), p. E668-E675
Abstract:
In estimating glucose and fructose 6-phosphate futile cycling in vivo, complete detritiation of [2-3H]glucose is assumed at the glucose 6-phosphate level, [3-3H] glucose at triose phosphate formation, and [6-3H]glucose in its conversion to glucose via pyruvate. [3-3H] glucose detritiation via the pentose cycle is assumed to be negligible. Normal and non-insulin-dependent diabetic subjects, in the basal state and infused with glucose, were given [2-3H,2-14C]galactose, and 3H-to-14C ratios in blood glucose were determined. [2-3H,2-14C] glucose was given with acetaminophen, and 3H/14C in urinary glucuronide was determined. Detritiation at glucose 6-phosphate was approximately 80%. [3-3H,1-14C]fructose was infused, and 3H/14C was determined in blood glucose and urinary glucuronide. At triose phosphate, 75-90% of the 3H was removed. The pentose cycle contribution was only a few percent. [6-3H,6-14C] glucose was infused, and 3H/14C in blood lactate was determined. [3-3H,3-14C]lactate was infused, and ratios in blood glucose were determined. Maximally, 10% of 3H from [6-3H] glucose was retained. If glucose and galactose are metabolized in the same hepatic site(s), glucose conversion to three-carbon intermediates in the indirect pathway of glycogen formation occurs in extrahepatic tissue(s). Reported estimates of futile cycling, although qualitatively correct, quantitatively require correction.
Type of Medium:
Online Resource
ISSN:
0193-1849
,
1522-1555
DOI:
10.1152/ajpendo.1989.256.5.E668
Language:
English
Publisher:
American Physiological Society
Publication Date:
1989
detail.hit.zdb_id:
1477331-4
SSG:
12
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