Stimulation of non-oxidative glucose utilization by L-carnitine in isolated myocytes

Salah Abdel-Aleem, Mohamed Sayed-Ahmed, Mohamed A. Nada, Steven C. Hendrickson, James St Louis, James E. Lowe

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The effects of L-carnitine on 14CO2 release from [1-14C]pyruvate oxidation (an index of pyruvate dehydrogenase activity, PDH), [2-14C]pyruvate, and [6-14C]glucose oxidation (indices of the acetyl-CoA flux through citric acid cycle), and [U-14C]glucose (an index of both PDH activity and the flux of acetyl-CoA through the citric acid cycle), were studied using isolated rat cardiac myocytes. L-carnitine increased the release of 14CO2 from [1-14C]pyruvate, and decreased that of [2-14C]pyruvate in a time and concentration-dependent manner. At a concentration of 2.5 mM, L-carnitine produced a 50% increase of CO2 release from [1-14C]pyruvate and a 50% decrease from [2-14C]pyruvate oxidation. L-carnitine also increased CO2 release from [1-14C[pyruvate oxidation by 35%, and decreased that of [2-14C]pyruvate oxidation 30%, in isolated rat heart mitochondria. The fatty acid oxidation inhibitor, etomoxir, stimulated the release of CO2 from both [1-14C]pyruvate and [2-14C]pyruvate. These results were supported by the effects of L-carnitine on the CO2 release from [6-14C]- and [U-14C]glucose oxidation. L-carnitine (5 mM) decreased the CO2 release from [6-14C]glucose by 37%, while etomoxir (50 μM) increased its release by 24%. L-carnitine had no effect on the oxidation of [U-14C]glucose. L-carnitine increased palmitate oxidation in a time- and concentration-dependent manner in myocytes. Also, it increased the rate of efflux of acetylcarnitine generated from pyruvate in myocytes. These results suggest that L-carnitine stimulates pyruvate dehydrogenase complex activity and enhances non-oxidative glucose metabolism by increasing the mitochondrial acetylcarnitine efflux in the absence of exogenous fatty acids.

Original languageEnglish (US)
Pages (from-to)2465-2472
Number of pages8
JournalJournal of molecular and cellular cardiology
Volume27
Issue number11
DOIs
StatePublished - Nov 1995
Externally publishedYes

Keywords

  • Cardiac myocytes
  • Glucose oxidation
  • L-carnitine
  • Pyruvate dehydrogenase

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Fingerprint Dive into the research topics of 'Stimulation of non-oxidative glucose utilization by L-carnitine in isolated myocytes'. Together they form a unique fingerprint.

Cite this