Calcium uptake by isolated nuclei was mediated by nicotinamide adenine dinucleotide. Oxidized nicotinamide nucleotide analogues were more effective mediators of nuclear calcium uptake. Thapsigargin inhibited ATP-mediated nuclear calcium transport without affecting NAD-mediated nuclear calcium uptake. Whilst DBHQ did not influence ATP-induced calcium transport, it did stimulate NAD-mediated nuclear calcium entry. Calcium channel blockers did not influence the action of NAD. This study provides a further mechanism for nuclear calcium transport regulated by changes in the cytosolic NAD+/NADH ratio.
