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Title: Effects of Continuous Triiodothyronine Infusion on Citric Acid Cycle in the Normal Immature Swine Heart under Extracorporeal Membrane Oxygenation in vivo

Extracorporeal membrane oxygenation (ECMO) is frequently used in infants with postoperative cardiopulmonary failure. ECMO also suppresses circulating triiodothyronine (T 3) levels and modifies myocardial metabolism. We assessed the hypothesis that T 3 supplementation reverses ECMO induced metabolic abnormalities in the immature heart. Twenty-two male Yorkshire pigs (age 25-38 days) with ECMO were received [2- 13C]lactate, [2,4,6,8- 13C]octanoate (medium chain fatty acid) and [U- 13C]long-chain fatty acids as metabolic tracers either systemically (totally physiological intracoronary concentration) or directly into the coronary artery (high substrate concentration) for the last 60 minutes of each protocol. Nuclear magnetic resonance (NMR) analysis of left ventricular tissue determined the fractional contribution (Fc) of these substrates to the citric acid cycle (CAC). Fifty percent of the pigs in each group received intravenous T 3 supplement (bolus at 0.6 μg/kg and then continuous infusion at 0.2 μg/kg/hour) during ECMO. Under both substrate loading conditions T 3 significantly increased lactate-Fc with a marginal increase in octanoate-Fc. Both T 3 and high substrate provision increased myocardial energy status indexed by [Phosphocreatine]/[ATP]. In conclusion, T 3 supplementation promoted lactate metabolism to the CAC during ECMO suggesting that T 3 releases inhibition of pyruvate dehydrogenase. Manipulation of substrate utilization by T 3more » may be used therapeutically during ECMO to improve resting energy state and facilitate weaning.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [2] ;  [2]
  1. Seattle Children's Research Inst., Seattle, WA (United States)
  2. Seattle Children's Research Inst., Seattle, WA (United States); Univ. of Washington, Seattle, WA (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
1158469
Report Number(s):
PNNL-SA-100172
Journal ID: ISSN 0363-6135; 48162; 600306000
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Journal of Physiology: Heart and Circulatory Physiology; Journal Volume: 306; Journal Issue: 8
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; cardiac metabolism; extracorporeal circulation; fatty acids; pediatrics; thyroid hormone; citric acid cycle; Environmental Molecular Sciences Laboratory