Cyclic nucleotide phosphodiesterase with specificity for the second messengers cAMP and cGMP, which are key regulators of many important physiological processes (PubMed:1315035, PubMed:8695850, PubMed:8155697, PubMed:25961942). Has also activity toward cUMP (PubMed:27975297). Independently of its catalytic activity it is part of an E2/17beta-estradiol-induced pro-apoptotic signaling pathway. E2 stabilizes the PDE3A/SLFN12 complex in the cytosol, promoting the dephosphorylation of SLFN12 and activating its pro-apoptotic ribosomal RNA/rRNA ribonuclease activity. This apoptotic pathway might be relevant in tissues with high concentration of E2 and be for instance involved in placenta remodeling (PubMed:31420216, PubMed:34707099).

This protein mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient (PubMed:1309946, PubMed:21447824, PubMed:25370050, PubMed:23420830, PubMed:23085483, PubMed:26279430, PubMed:26392562, PubMed:26776555). It is a tetrodotoxin-resistant Na(+) channel isoform (PubMed:1309946). This channel is responsible for the initial upstroke of the action potential. Channel inactivation is regulated by intracellular calcium levels (PubMed:19074138).