SN Hussain, A Giaid, Q El Dawiri, D Sakkal, R Hattori and Y Guo
Critical Division, Royal Victoria Hospital, Montreal, Quebec, Canada. SHUSSAIN@RVHMED.LAN.MCGILL.CA

Nitric oxide synthases (NOS) convert L-arginine to nitric oxide in the presence of tetrahydrobiopterin (BH4). Two constitutive isoforms of NOS exist in normal skeletal muscle fibers, however, the existence of a third, the inducible isoform (iNOS), has never been detected in these fibers in vivo. Therefore, we assessed the influence of in vivo endotoxemia on skeletal muscle expression of constitutive and inducible NOS isoforms and GTP cyclohydrolase I, the rate limiting enzyme of BH4 synthesis. Two groups of rats were infused i.p. either with E. coli endotoxin (20 mg/kg, LPS group) or saline (saline group). Animals were killed 6 h later and the ventilatory and limb muscles were quickly frozen. Endotoxin infusion elicited a significant rise in NOS activity of the diaphragm, intercostal, soleus and gastrocnemius muscles. Reverse transcription-polymerase chain reaction (RT-PCR) on muscle total RNA detected very low expression of iNOS and GTP cyclohydrolase I mRNA in the saline group, but significant upregulation of both enzymes was found in the ventilatory and limb muscles of the LPS group. Immunoblotting detected no iNOS protein in the saline group but a significant iNOS protein expression was found in the diaphragm, intercostal and soleus muscles and to a lesser extent, in the gastrocnemius of the LPS group. Endotoxemia was also associated with increased protein expression of constitutive NOS isoforms mainly in the diaphragm and to lesser extent in the intercostal, gastrocnemius and soleus muscles. We conclude that in vivo exposure to endotoxin leads to differential induction of both iNOS and GTP cyclohydrolase I in the ventilatory and limb muscles.

This article has been cited by other articles:

				M. Divangahi, A. Demoule, G. Danialou, L. Yahiaoui, W. Bao, Z. Xing, and B. J. Petrof Impact of IL-10 on Diaphragmatic Cytokine Expression and Contractility during Pseudomonas Infection Am. J. Respir. Cell Mol. Biol., April 1, 2007; 36(4): 504 - 512. [Abstract] [Full Text] [PDF]

				T. Vassilakopoulos, K. Govindaraju, D. Parthenis, D. H. Eidelman, Y. Watanabe, and S. N. A. Hussain Nitric oxide production in the ventilatory muscles in response to acute resistive loading Am J Physiol Lung Cell Mol Physiol, April 1, 2007; 292(4): L1013 - L1022. [Abstract] [Full Text] [PDF]

				A. Demoule, M. Divangahi, L. Yahiaoui, G. Danialou, D. Gvozdic, K. Labbe, W. Bao, and B. J. Petrof Endotoxin Triggers Nuclear Factor-{kappa}B-dependent Up-regulation of Multiple Proinflammatory Genes in the Diaphragm Am. J. Respir. Crit. Care Med., September 15, 2006; 174(6): 646 - 653. [Abstract] [Full Text] [PDF]

				E. Barreiro, B. de la Puente, J. Minguella, J. M. Corominas, S. Serrano, S. N. A. Hussain, and J. Gea Oxidative Stress and Respiratory Muscle Dysfunction in Severe Chronic Obstructive Pulmonary Disease Am. J. Respir. Crit. Care Med., May 15, 2005; 171(10): 1116 - 1124. [Abstract] [Full Text] [PDF]

				R. A. Frost, G. J. Nystrom, and C. H. Lang Lipopolysaccharide stimulates nitric oxide synthase-2 expression in murine skeletal muscle and C2C12 myoblasts via Toll-like receptor-4 and c-Jun NH2-terminal kinase pathways Am J Physiol Cell Physiol, December 1, 2004; 287(6): C1605 - C1615. [Abstract] [Full Text] [PDF]

				J. W. Skimming, O. Nasiroglu, C.-J. Huang, C. E. Wood, B. R. Stevens, I. U. L. Haque, P. O. Scumpia, and P. J. Sarcia Dexamethasone suppresses iNOS yet induces GTPCH and CAT-2 mRNA expression in rat lungs Am J Physiol Lung Cell Mol Physiol, August 1, 2003; 285(2): L484 - L491. [Abstract] [Full Text] [PDF]

				T. Vassilakopoulos, G. Deckman, M. Kebbewar, G. Rallis, R. Harfouche, and S. N. A. Hussain Regulation of nitric oxide production in limb and ventilatory muscles during chronic exercise training Am J Physiol Lung Cell Mol Physiol, March 1, 2003; 284(3): L452 - L457. [Abstract] [Full Text] [PDF]

				E. Barreiro, A. S. Comtois, S. Mohammed, L. C. Lands, and S. N. A. Hussain Role of heme oxygenases in sepsis-induced diaphragmatic contractile dysfunction and oxidative stress Am J Physiol Lung Cell Mol Physiol, August 1, 2002; 283(2): L476 - L484. [Abstract] [Full Text] [PDF]

				D. JAVESGHANI, S. A. MAGDER, E. BARREIRO, M. T. QUINN, and S. N. A. HUSSAIN Molecular Characterization of a Superoxide-Generating NAD(P)H Oxidase in the Ventilatory Muscles Am. J. Respir. Crit. Care Med., February 1, 2002; 165(3): 412 - 418. [Abstract] [Full Text] [PDF]

				K. Nishina, K. Mikawa, S.-i. Kodama, and H. Obara ONO1714, a New Inducible Nitric Oxide Synthase Inhibitor, Attenuates Sepsis-Induced Diaphragmatic Dysfunction in Hamsters Anesth. Analg., April 1, 2001; 92(4): 959 - 966. [Abstract] [Full Text] [PDF]

				A. S. COMTOIS, E. BARREIRO, P. L. HUANG, A. MARETTE, M. PERRAULT, and S. N. A. HUSSAIN Lipopolysaccharide-induced Diaphragmatic Contractile Dysfunction and Sarcolemmal Injury in Mice Lacking the Neuronal Nitric Oxide Synthase Am. J. Respir. Crit. Care Med., March 15, 2001; 163(4): 977 - 982. [Abstract] [Full Text]

				S. Gallinat, S. Busche, H. Yang, M. K. Raizada, and C. Sumners Gene Expression Profiling of Rat Brain Neurons Reveals Angiotensin II-Induced Regulation of Calmodulin and Synapsin I: Possible Role in Neuromodulation Endocrinology, March 1, 2001; 142(3): 1009 - 1016. [Abstract] [Full Text] [PDF]

				J. S. Stamler and G. Meissner Physiology of Nitric Oxide in Skeletal Muscle Physiol Rev, January 1, 2001; 81(1): 209 - 237. [Abstract] [Full Text] [PDF]

				D. Javeshghani, D. Sakkal, M. Mori, and S. N. A. Hussain Regulation of diaphragmatic nitric oxide synthase expression during hypobaric hypoxia Am J Physiol Lung Cell Mol Physiol, September 1, 2000; 279(3): L520 - L527. [Abstract] [Full Text] [PDF]

				W. Hirschfield, M. R. Moody, W. E. O'Brien, A. R. Gregg, R. M. Bryan Jr., and M. B. Reid Nitric oxide release and contractile properties of skeletal muscles from mice deficient in type III NOS Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2000; 278(1): R95 - R100. [Abstract] [Full Text] [PDF]

				A. S. COMTOIS, Q. EL-DWAIRI, V. E. LAUBACH, and S. N. A. HUSSAIN Lipopolysaccharide-induced Diaphragmatic Contractile Dysfunction in Mice Lacking the Inducible Nitric Oxide Synthase Am. J. Respir. Crit. Care Med., June 1, 1999; 159(6): 1975 - 1980. [Abstract] [Full Text]

				Y. Fujii, Y. Guo, and S. N. A. Hussain Regulation of nitric oxide production in response to skeletal muscle activation J Appl Physiol, December 1, 1998; 85(6): 2330 - 2336. [Abstract] [Full Text] [PDF]

				M. Fukuchi, S. N. A. Hussain, and A. Giaid Heterogeneous Expression and Activity of Endothelial and Inducible Nitric Oxide Synthases in End-Stage Human Heart Failure : Their Relation to Lesion Site and ß-Adrenergic Receptor Therapy Circulation, July 14, 1998; 98(2): 132 - 139. [Abstract] [Full Text] [PDF]