"Clocks" in the NAD World: NAD as a metabolic oscillator for the regulation of metabolism and aging.
- Shin-Ichiro Imai
- Biochimica et biophysica acta
Kinetic studies of nicotinamide adenine dinucleotide phosphate autofluorescence have been conducted in adherent neutrophils using an improved microscopic photometry system incorporating low noise excitation and detection systems. Dynamic autofluorescence oscillations were found with periods ranging from ∼4 min to ∼10 s. The largest portion of the population of oscillating neutrophils (32%) had periods near 2 min. The next largest group at 25% exhibited periods of 1 min or less. These oscillations could not be accounted for by instrument artifacts, cell shape changes away from the focal plane, or other factors. They disappeared when detergent was added to oscillating cells. Higher-frequency oscillations disappeared as cells changed shape, indicating a correlation between these two processes. This approach provides a reliable method to monitor this cellular property.