31P-NMR studies of respiratory regulation in the intact myocardium

Arthur H From, Marc A. Petein, Steven P. Michurski, Stevan D. Zimmer, Kamil Ugurbil

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

The mechanism by which mitochondrial respiration is coupled to ATP consumption in intact tissues is unclear. We determined the relationship between high-energy phosphate levels and oxygen consumption rate in rat hearts operating over a range of workloads and perfused with different substrates. With pyruvate + glucose perfusion, ADP levels were in general very low, and varied with MVO2 yielding an apparent Km of 25 ± 5 μM, suggesting regulation of oxidative phosphorylation through availability of ADP. In contrast, with glucose perfusion in the presence or absence of insulin, ADP levels, ADP/ATP ratio or the phosphate potential were relatively constant over the workload range examined and generally not correlated with alterations in MVO2; it is suggested that under these conditions, carbon substrate delivery to the mitochondria may control mitochondrial respiration. The common feature of both of the suggested regulatory mechanisms is substrate limitation which, however, is exercised at different metabolic points depending on the carbon substrate available to the myocardium.

Original languageEnglish (US)
Pages (from-to)257-261
Number of pages5
JournalFEBS Letters
Volume206
Issue number2
DOIs
StatePublished - Oct 6 1986

Bibliographical note

Funding Information:
Supported by NIH 1K 04-HLO1241 and ResearchF unds.

Keywords

  • (Rat myocardium)
  • P-NMR
  • Respiratory regulation
  • Substrate dependence

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