NADH augments blood flow in physiologically activated retina and visual cortex

NADH augments blood flow in physiologically activated retina and visual cortex

The mechanism(s) that increase retinal and visual cortex blood
flows in response to visual stimulation are poorly understood. We
tested the hypothesis that increased transfer of electrons and
protons from glucose to cytosolic free NAD, reducing it to NADH,
evoked by increased energy metabolism, fuels redox-signaling
pathways that augment flow. The near-equilibrium between free
cytosolic NADHNAD and lactatepyruvate ratios established by
lactate dehydrogenase predicts that transfer of additional electrons
and protons from injected lactate to NAD will augment the
elevated blood flows in stimulated retina and cortex, whereas
transfer of electrons and protons from NADH to injected pyruvate
will attenuate the elevated flows. These predictions were tested
and confirmed in rats. Increased flows evoked by stimulation also
were prevented by inhibition of nitric oxide synthase. These
findings support an important role for cytosolic free NADH in
fueling a signaling cascade that increases •NO production, which
augments blood flow in photostimulated retina and visual cortex…

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