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The changes in the ratio of free cytosolic [NAD+]/[NADH] reflects metabolic alterations leading to, or correlating with,pathological states. We have designed an isotopically labelled metabolic bioprobe of free cytosolic[NAD+]/[NADH] by combining a magnetic enhancement technique (hyperpolarization) with cellular glycolytic activity. The bioprobe reports free cytosolic [NAD+]/[NADH] ratios based on dynamically measured in-cell [pyruvate]/ [lactate].alterations in metabolism that are often linked to
pathological states.NAD is either protein bound or free and separate
pools are present in the cytosol and in the
mitochondria of mammalian cells. Several direct
detection methods are commercially available for
measurement of the total cellular NAD+ and NADH
concentrations. Measurements of whole cell total
concentrations of NAD+ and NADH does, however,
not distinguish between pools in different
compartments or between free and protein bound
forms, and so can only provide information about the
ratio of the NAD+-NADH couple over all .
Most
NADH present in the mitochondria is protein bound
(10) and will not contribute to the cellular redox
potential. Whereas the total cellular [NAD+
]/[NADH] ratio is typically on the order of 2-4 (11,12) the free
cytosolic [NAD+]/[NADH] ratio is usually several
orders of magnitude higher .Thus the importance of the ratio of free cytosolic [NAD+]/[NADH] to the cellular redox potential has lead to a focus on methods capable of estimating this
ratio.