NPPA and atrial fibrillation: (6) When the NPPA encoding gene of natriuretic peptide precursor A is mutated, the cGMP level is up-regulated, the cAMP level and PKA activity are down-regulated, the cardiac sodium and calcium current is weakened, the rectified potassium current is enhanced, the action potential duration is shortened, and re-entrant atrial fibrillation is promoted [105].