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Cardiovasc Diabetol. 2015 May 20;14:56. doi: 10.1186/s12933-015-0223-2.

Tissue inflammation and nitric oxide-mediated alterations in cardiovascular function are major determinants of endotoxin-induced insulin resistance.

Author information

1
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. lmclhouse2@gmail.com.
2
College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA. lmclhouse2@gmail.com.
3
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. tmorris@missouristate.edu.
4
Department of Biomedical Sciences, Missouri State University, Springfield, MO, USA. tmorris@missouristate.edu.
5
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. lundblad.tammy@gmail.com.
6
Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA. lundblad.tammy@gmail.com.
7
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. louise.lantier@vanderbilt.edu.
8
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. travis.j.cyphert@vanderbilt.edu.
9
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. owen.mcguinness@vanderbilt.edu.
10
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN, 37232, USA. yolanda.otero@vanderbilt.edu.

Abstract

BACKGROUND:

Endotoxin (i.e. LPS) administration induces a robust inflammatory response with accompanying cardiovascular dysfunction and insulin resistance. Overabundance of nitric oxide (NO) contributes to the vascular dysfunction. However, inflammation itself also induces insulin resistance in skeletal muscle. We sought to investigate whether the cardiovascular dysfunction induced by increased NO availability without inflammatory stress can promote insulin resistance. Additionally, we examined the role of inducible nitric oxide synthase (iNOS or NOS2), the source of the increase in NO availability, in modulating LPS-induced decrease in insulin-stimulated muscle glucose uptake (MGU).

METHODS:

The impact of NO donor infusion on insulin-stimulated whole-body and muscle glucose uptake (hyperinsulinemic-euglycemic clamps), and the cardiovascular system was assessed in chronically catheterized, conscious mice wild-type (WT) mice. The impact of LPS on insulin action and the cardiovascular system were assessed in WT and global iNOS knockout (KO) mice. Tissue blood flow and cardiac function were assessed using microspheres and echocardiography, respectively. Insulin signaling activity, and gene expression of pro-inflammatory markers were also measured.

RESULTS:

NO donor infusion decreased mean arterial blood pressure, whole-body glucose requirements, and MGU in the absence of changes in skeletal muscle blood flow. LPS lowered mean arterial blood pressure and glucose requirements in WT mice, but not in iNOS KO mice. Lastly, despite an intact inflammatory response, iNOS KO mice were protected from LPS-mediated deficits in cardiac output. LPS impaired MGU in vivo, regardless of the presence of iNOS. However, ex vivo, insulin action in muscle obtained from LPS treated iNOS KO animals was protected.

CONCLUSION:

Nitric oxide excess and LPS impairs glycemic control by diminishing MGU. LPS impairs MGU by both the direct effect of inflammation on the myocyte, as well as by the indirect NO-driven cardiovascular dysfunction.

PMID:
25986700
PMCID:
PMC4484635
DOI:
10.1186/s12933-015-0223-2
[Indexed for MEDLINE]
Free PMC Article

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