NADPH oxidase- and mitochondrion-derived superoxide at rostral ventrolateral medulla in endotoxin-induced cardiovascular depression.
We evaluated the contribution of superoxide anion (O2*-) generated by NADPH oxidase or mitochondria in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons for arterial pressure maintenance are located, on cardiovascular depression induced by inducible nitric oxide synthase-derived NO after Escherichia coli lipopolysaccharide (LPS) treatment. In Sprague-Dawley rats maintained under propofol anesthesia, microinjection of LPS bilaterally into the RVLM induced progressive hypotension, bradycardia, and reduction in sympathetic vasomotor outflow over our 240-min observation period. This was accompanied by an increase in O2*- production (60-240 min) in the RVLM, alongside phosphorylation of p47(phox) or p67(phox), upregulation of gp91(phox) or p47(phox) protein, and increase in Rac-1 or NADPH oxidase activity (60-120 min), and a depression of mitochondrial respiratory enzyme activity (120-240 min). Whereas inhibition of NADPH oxidase or knockdown of the gp91(phox) or p47(phox) gene blunted the early phase (60-150 min), coenzyme Q10 or mitochondrial K(ATP) channel inhibitor antagonized the delayed phase (120-240 min) of LPS-induced increase in O2*- production in RVLM and cardiovascular depression. We conclude that, whereas NADPH oxidase-derived O2*- in RVLM participates predominantly in the early phase, O2*- generated by depression in mitochondrial respiratory enzyme activity or opening of mitoK(ATP) channels mediates the delayed phase of LPS-induced cardiovascular depression.
Sheh
Yen-Ling
YL
Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, Republic of China.
Hsu
Chin
C
Chan
Samuel H H
SH
Chan
Julie Y H
JY
D000818:Animals; D002318:Cardiovascular Diseases / Q000139:chemically induced / Q000378:metabolism*; D004731:Endotoxins / Q000633:toxicity; D020547:Lateral Ventricles / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D015221:Potassium Channels / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000378:metabolism*; D015854:Up-Regulation; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D004731:Endotoxins; D008562:Membrane Glycoproteins; D015221:Potassium Channels; C117780:mitochondrial K(ATP) channel; D013481:Superoxides; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein