Nicotinamide inhibition of 3′,5′- cyclic AMP phosphodiesterase in vitro

Nicotinamide was found to be potent inhibitor of 3′,5′- cyclic AMP phosphodiesterase, but nicotinamide adenine dinucleotide was found impotent. Therefore, it may be presumed that the induction of certain enzymes following the intraperitoneal injection of nicotinamide into rats would due to the elevation of the steady state level of 3′,5′- cyclic AMP through the inhibition of phosphodiesterase by nicotinamide.