I'm frequently asked why we quantify the NAD metabolome in whole blood & not in PBMCs, plasma or serum. The 4 NAD coenzymes are intracellular metabolites & almost entirely found in the cellular fraction. When ppl prep plasma, they are literally throwing away >99% of the NAD+ /1
in the discarded cell fraction. They are also breaking ~1% of the cells, spilling NAD+ & NADP+ into plasma. The longer before you snap-freeze blood, the more you break cells & degrade metabolites. There is nothing to be gained & everything to be lost by prepping PBMCs /2
Plasma NAD+ is meaningless unless you want to use it as a measure of cell breakage /end #garbageingarbageout
