Importance of blood glucose concentration in regulating lipolysis during fasting in humans

S. Klein, O. B. Holland, R. R. Wolfe

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

The importance of the decline in blood glucose concentration on lipolysis and the lipolytic effect of epinephrine was evaluated during short-term fasting. Lipolytic rates were determined by infusing [2H5]glycerol and [1-13C]palmitic acid. Five volunteers were studied after 12 h of fasting before and during epinephrine infusion and after 84 h of fasting, before and during glucose infusion when plasma glucose was restored to postabsorptive values, and during glucose plus epinephrine infusion. In another protocol, five volunteers were given glucose intravenously throughout fasting to maintain plasma glucose at postabsorptive levels and isotopic studies were performed after 12 and 84 h of fasting before and during epinephrine infusion. Glucose infusion after 84 h of fasting restored glucose and insulin concentrations and lipolytic rates toward 12-h fasting values. When euglycemia was maintained throughout fasting, plasma insulin still declined (P < 0.05) and lipolytic rates still increased (P < 0.05). Despite similar glucose concentrations, the lipolytic response to epinephrine infusion was greater after 84 h than after 12 h of fasting in both protocols (P < 0.05). These studies demonstrate that the decline in plasma glucose contributes to, but is not required for, the increase in lipolysis during fasting. The increase in epinephrine-stimulated lipolysis that occurs during fasting is not dependent on a decrease in plasma glucose concentration.

Original languageEnglish (US)
Pages (from-to)E32-E39
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume258
Issue number1 21-1
DOIs
StatePublished - 1990

Keywords

  • fatty acid flux
  • glycerol flux
  • stable isotopes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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