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1Department of Physiology; and 2Neuroscience Program, Michigan State University, East Lansing, Michigan
Submitted 18 January 2005 ; accepted in final form 1 October 2005
Superoxide anion (O2–·) production is elevated in sympathetic ganglion neurons and in the vasculature of hypertensive animals; however, it is not known what enzymatic pathway(s) are responsible for O2–· production. To determine the pathway(s) of O2–· production in sympathetic neurons, we examined the presence of mRNA of NADPH oxidase subunits in sympathetic ganglionic neurons and differentiated PC-12 cells. The mRNAs for NADPH oxidase subunits p47phox, p22phox, gp91phox, and NOX1 were present in sympathetic neurons and PC-12 cells, whereas the NOX4 homologue was present in sympathetic neurons but not PC-12 cells. Freshly dissociated celiac ganglion neurons from normal rats and PC-12 cells produced O2–· when treated with the PKC activator PMA; O2–· production increased by 317% and 254%, respectively. The PMA-evoked increases were reduced by pretreatment with the NADPH oxidase inhibitor apocynin. These findings indicate that NADPH oxidase is the primary source of O2–· in sympathetic ganglion neurons. When celiac ganglia from hypertensive rats were incubated with apocynin, O2–· levels were reduced to the same levels as normotensive animals, indicating that NADPH oxidase activity accounted for the elevated O2–· levels in hypertensive animals. To test this latter finding, we compared NADPH oxidase activity in extracts of prevertebral sympathetic ganglia of DOCA-salt hypertensive rats and sham-operated rats. NADPH oxidase activities were 49.9% and 78.6% higher in sympathetic ganglia of DOCA rats compared with normotensive controls when using 
-NADH and -NADPH as substrates, respectively. Thus elevated O2–· levels in hypertension may be a result of the increased activity of NADPH oxidase in postganglionic sympathetic neurons.
sympathetic ganglia; phorbol ester; reduced nicotinamide adenine dinucleotide phosphate oxidase; hypertension; deoxycorticosterone acetate
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