Altered carnitine homeostasis is associated with decreased mitochondrial function and altered nitric oxide signaling in lambs with pulmonary hypertension

Shruti Sharma, Neetu Sud, Dean A. Wiseman, A. Lee Carter, Sanjiv Kumar, Yali Hou, Thomas Rau, Jason Wilham, Cynthia Harmon, Peter Oishi, Jeffrey R. Fineman, Stephen M. Black

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Utilizing aortopulmonary vascular graft placement in the fetal lamb, we have developed a model (shunt) of pulmonary hypertension that mimics congenital heart disease with increased pulmonary blood flow. Our previous studies have identified a progressive development of endothelial dysfunction in shunt lambs that is dependent, at least in part, on decreased nitric oxide (NO) signaling. The purpose of this study was to evaluate the possible role of a disruption in carnitine metabolism in shunt lambs and to determine the effect on NO signaling. Our data indicate that at 2 wk of age, shunt lambs have significantly reduced expression (P < 0.05) of the key enzymes in carnitine metabolism: carnitine palmitoyltransferases 1 and 2 as well as carnitine acetyltransferase (CrAT). In addition, we found that CrAT activity was inhibited due to increased nitration. Furthermore, free carnitine levels were significantly decreased whereas acylcarnitine levels were significantly higher in shunt lambs (P < 0.05). We also found that alterations in carnitine metabolism resulted in mitochondrial dysfunction, since shunt lambs had significantly decreased pyruvate, increased lactate, and a reduced pyruvate/lactate ratio. In pulmonary arterial endothelial cells cultured from juvenile lambs, we found that mild uncoupling of the mitochondria led to a decrease in cellular ATP levels and a reduction in both endothelial NO synthase-heat shock protein 90 (eNOS-HSP90) interactions and NO signaling. Similarly, in shunt lambs we found a loss of eNOS-HSP90 interactions that correlated with a progressive decrease in NO signaling. Our data suggest that mitochondrial dysfunction may play a role in the development of endothelial dysfunction and pulmonary hypertension and increased pulmonary blood flow.

Original languageEnglish (US)
Pages (from-to)L46-L56
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume294
Issue number1
DOIs
StatePublished - Jan 1 2008

Fingerprint

Carnitine
Pulmonary Hypertension
Nitric Oxide
Homeostasis
Carnitine O-Acetyltransferase
HSP90 Heat-Shock Proteins
Pyruvic Acid
Lung
Lactic Acid
Carnitine O-Palmitoyltransferase
Nitric Oxide Synthase Type III
Nitric Oxide Synthase
Blood Vessels
Heart Diseases
Mitochondria
Endothelial Cells
Adenosine Triphosphate
Transplants
Enzymes

Keywords

  • Carnitine metabolism
  • Oxidative stress

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

Cite this

Altered carnitine homeostasis is associated with decreased mitochondrial function and altered nitric oxide signaling in lambs with pulmonary hypertension. / Sharma, Shruti; Sud, Neetu; Wiseman, Dean A.; Carter, A. Lee; Kumar, Sanjiv; Hou, Yali; Rau, Thomas; Wilham, Jason; Harmon, Cynthia; Oishi, Peter; Fineman, Jeffrey R.; Black, Stephen M.

In: American Journal of Physiology - Lung Cellular and Molecular Physiology, Vol. 294, No. 1, 01.01.2008, p. L46-L56.

Research output: Contribution to journalArticle

Sharma, Shruti ; Sud, Neetu ; Wiseman, Dean A. ; Carter, A. Lee ; Kumar, Sanjiv ; Hou, Yali ; Rau, Thomas ; Wilham, Jason ; Harmon, Cynthia ; Oishi, Peter ; Fineman, Jeffrey R. ; Black, Stephen M. / Altered carnitine homeostasis is associated with decreased mitochondrial function and altered nitric oxide signaling in lambs with pulmonary hypertension. In: American Journal of Physiology - Lung Cellular and Molecular Physiology. 2008 ; Vol. 294, No. 1. pp. L46-L56.
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AU - Sud, Neetu

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AU - Carter, A. Lee

AU - Kumar, Sanjiv

AU - Hou, Yali

AU - Rau, Thomas

AU - Wilham, Jason

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AU - Oishi, Peter

AU - Fineman, Jeffrey R.

AU - Black, Stephen M.

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AB - Utilizing aortopulmonary vascular graft placement in the fetal lamb, we have developed a model (shunt) of pulmonary hypertension that mimics congenital heart disease with increased pulmonary blood flow. Our previous studies have identified a progressive development of endothelial dysfunction in shunt lambs that is dependent, at least in part, on decreased nitric oxide (NO) signaling. The purpose of this study was to evaluate the possible role of a disruption in carnitine metabolism in shunt lambs and to determine the effect on NO signaling. Our data indicate that at 2 wk of age, shunt lambs have significantly reduced expression (P < 0.05) of the key enzymes in carnitine metabolism: carnitine palmitoyltransferases 1 and 2 as well as carnitine acetyltransferase (CrAT). In addition, we found that CrAT activity was inhibited due to increased nitration. Furthermore, free carnitine levels were significantly decreased whereas acylcarnitine levels were significantly higher in shunt lambs (P < 0.05). We also found that alterations in carnitine metabolism resulted in mitochondrial dysfunction, since shunt lambs had significantly decreased pyruvate, increased lactate, and a reduced pyruvate/lactate ratio. In pulmonary arterial endothelial cells cultured from juvenile lambs, we found that mild uncoupling of the mitochondria led to a decrease in cellular ATP levels and a reduction in both endothelial NO synthase-heat shock protein 90 (eNOS-HSP90) interactions and NO signaling. Similarly, in shunt lambs we found a loss of eNOS-HSP90 interactions that correlated with a progressive decrease in NO signaling. Our data suggest that mitochondrial dysfunction may play a role in the development of endothelial dysfunction and pulmonary hypertension and increased pulmonary blood flow.

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