Final answer:
In a fasted state, phosphodiesterase (PDE) is generally on and deactivates cyclic AMP (cAMP), a second messenger in cell signaling.
Step-by-step explanation:
In a fasted state, phosphodiesterase (PDE) is generally on. PDE is an enzyme that deactivates and degrades cyclic AMP (cAMP), which is a second messenger involved in cell signaling. When cAMP is deactivated by PDE, the signaling cascade triggered by hormones ceases quickly unless new hormones arrive at the cell membrane.