Sidney, just saw your reply so decided to address it separately.
There is a problem with the whole idea of mito's making ONOO - that is that
NO has to get into the mito's, or O2.- has to get out (probably the former
as the latter has never been proven). By the way, this is my chief
argument against the existance of a mitochondrial NOS - if it was inside
the mito's next to a known source of O2.- it would just be a peroxynitrite
factory!
There is some evidence from Poderoso et al, saying that inhibition of
mitochondria by NO increases their H2O2 production, but unfortunately they
used homovanillic acid/horseradish peroxidase detection system, which is
totally non-specific (it detects just about every radical). I tried to
repeat the same experiments using brain mito's, and found that NO alone
reacts with components of various buffer systems to produce something
(whatever it is) that gives a signal in an HVA/HRP system. Even Mike
Packer's work showing that mito's + NO leads to increased
1,2,3-dihydrorhodamine fluoresence is let down by the fact that DHR is not
really that specific for ONOO-.
Is there any evidence that activated macrophages are elevated in Parkinsons
or similar syndromes? Do they get through the blood-brain-barrier? (I
thought they couldn't). Is there any epidemiological evidence of
Parkinsons being related to bacterial infections? Also, how much NO does
neuronal NOS make - I thought it was about 1/1000th of the amount iNOS makes.
Its OK to speculate about mitochondrial O2.- and NO coming together to make
ONOO-, and if you put them next to each other in a test tube they'll do it,
but whether such things actually occur in vivo, especially taking
compartmentation into account, remains to be seen.
Wonder if I can make outer membrane liposomes and measure their
permeability to NO, that'd be interesting?
Paul
______________________________________________
Dr. Paul S. Brookes. (brookes at uab.edu)
UAB Department of Pathology, G004 Volker Hall
1670 University Blvd., Birmingham AL 35294 USA
Tel (001) 205 934 1915 Fax (001) 205 934 1775
http://peir.path.uab.edu/brookes
