Despite minimal hemodynamic alterations endotoxemia modulates NOS and p38-MAPK phosphorylation via metalloendopeptidases.
In the present study, we hypothesized that endotoxemia produces metalloendopeptidase (MEPD)-dependent generation of endothelin-1 (ET-1) and alters NOS expression correlating with p38-mitogen-activated protein kinase (MAPK) phosphorylation in thoracic aorta. Male Sprague-Dawley rats (350-400 g) were subjected to two groups randomly; sham-treated (N = 10) and lipopolysaccharide (LPS)-treated (N = 10) (E. coli LPS 2 mg/kg bolus + 2 mg/kg infusion for 30 min). The animals in each group were further subdivided into vehicle and MEPD inhibitor phosphoramidon (1 mg/kg bolus, PHOS)-treated groups. LPS produces a significant decrease in mean arterial pressure (MAP) at 2 h post endotoxemia that was blocked by PHOS. PHOS attenuated LPS-induced increase in tumor necrosis factor-alpha (TNF-alpha) concentration at 2- and 24 h post-LPS administration. LPS significantly elevated plasma concentrations of ET-1 at 2- and 24 h post endotoxemia. An upregulated preproET-1 expression following both LPS and MEPD inhibition was observed in thoracic aorta at 2 h post treatment. PHOS effectively blocked conversion of preproET-1 to ET-1 in thoracic aorta locally at 24 h post treatment in endotoxic rats. PHOS inhibited LPS-induced upregulation of inducible NOS (iNOS), downregulation of endothelial NOS (eNOS) and elevation of NO byproducts (NOx) in thoracic aorta. PHOS also blocked LPS-induced upregulated p38-MAPK phosphorylation in thoracic aorta at 24 h post endotoxemia. The data revealed that LPS induces MEPD-sensitive inflammatory response syndrome (SIRS) at 2- and 24 h post endotoxemia. We concluded that inhibition of MEPD not only decreases the levels of ET-1 but also simultaneously downregulates protein expression of iNOS and phosphorylated p38-MAPK while increasing eNOS in thoracic aorta during SIRS in endotoxemia. We suggest that MEPD-dependent ET-1 and NO mechanisms may be involved in endotoxemia-induced altered p38-MAPK phosphorylation.
Gupta
Akanksha
A
Department of Pharmaceutical Sciences, Cardionome laboratories, College of Pharmacy, North Dakota State University, 208 Sudro Hall, Fargo, ND 58105, USA.
Sharma
Avadhesh C
AC
D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology; D001794:Blood Pressure; D016207:Cytokines / Q000096:biosynthesis; D019332:Endothelin-1 / Q000096:biosynthesis; D019446:Endotoxemia / Q000201:enzymology / Q000473:pathology*; D006020:Glycopeptides / Q000494:pharmacology; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000378:metabolism; D008297:Male; D008666:Metalloendopeptidases / Q000737:chemistry*; D008954:Models, Biological; D009569:Nitric Oxide / Q000737:chemistry; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D016207:Cytokines; D019332:Endothelin-1; D006020:Glycopeptides; D008070:Lipopolysaccharides; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D048051:p38 Mitogen-Activated Protein Kinases; D008666:Metalloendopeptidases; C008890:phosphoramidon