Lumped constant for deoxyglucose is decreased when myocardial glucose uptake is enhanced

Katsuji Hashimoto, Tsunehiko Nishimura, Ken Ichi Imahashi, Hitoshi Yamaguchi, Masatsugu Hori, Hideo Kusuoka

Research output: Contribution to journalArticle

Abstract

Quantification of myocardial glucose uptake by positron emission tomography with [18F]fluorodeoxyglucose (FDG) requires the 'lumped constant' (LC), which corrects the difference of affinity between glucose and FDG to glucose transporters and phosphorylating system. Since LC was introduced, it has been considered to be constant. However, this has recently been questioned. To elucidate the constancy of LC by other than radioisotope techniques, the accumulation rate of sugar phosphates (d[SP]/dt) was measured in isolated, perfused rat hearts by 31P NMR spectroscopy with 2- deoxyglucose (DG). We postulate α as the affinity of DG to transporters and the phosphorylating system relative to that of glucose. Theoretically, α is equivalent to LC. We determined α by measuring d[SP]/dt at DG concentration ([DG]) = 10, 7, 5, and 3 mmol/l, keeping the total of glucose concentration ([glucose]) and [DG] to 10 mmol/l. When the glucose uptake was enhanced by insulin (10 mU/ml) or stunning, calculated, was reduced (insulin stimulated, 0.15; stunning, 0.19) compared with the control (0.59). These results indicate that LC can be evaluated by methods without radiolabeled tracers and is smaller when glucose uptake is augmented.

Original languageEnglish (US)
Pages (from-to)H129-H133
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume276
Issue number1 45-1
DOIs
StatePublished - Jan 1999

Keywords

  • Insulin
  • Myocardial stunning
  • Nuclear magnetic resonance spectroscopy

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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