A correlation between soluble brain nitric oxide synthase and NADPH-diaphorase activity is only seen after exposure of the tissue to fixative.
In histochemical studies using fixed brain tissue, NADPH-diaphorase has been found to be colocalized with soluble nitric oxide synthase. In the present study, using fresh tissues from eight different regions of rat brain, NADPH-diaphorase activity was found mostly in the particulate fraction, whereas most of the nitric oxide synthase activity was located to the cytosolic fraction. Also, the distribution of NADPH-diaphorase activity among brain regions was different from that of nitric oxide synthase. Pretreatment of the fractions with paraformaldehyde virtually abolished the NADPH-diaphorase activity in the particulate fraction, whereas 40-60% of the NADPH-diaphorase activity remained intact in the cytosolic fraction. These results suggest that during fixation most NADPH-diaphorase activity is inactivated and only some of the NADPH-diaphorase activity associated with soluble nitric oxide synthase remains intact.
Matsumoto
T
T
Department of Pharmacology, Northwestern University Medical School, Chicago, IL 60611.
Nakane
M
M
Pollock
J S
JS
Kuk
J E
JE
Förstermann
U
U
D000594:Amino Acid Oxidoreductases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D005404:Fixatives / Q000494:pharmacology*; D005557:Formaldehyde / Q000494:pharmacology*; D009252:NADPH Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019001:Nitric Oxide Synthase; D011108:Polymers / Q000494:pharmacology*; D051381:Rats; D012995:Solubility; D013347:Subcellular Fractions / Q000201:enzymology; D014018:Tissue Distribution
D005404:Fixatives; D011108:Polymers; D005557:Formaldehyde; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D009252:NADPH Dehydrogenase; C003043:paraform