Vinpocetine was described as a specific inhibitor of basal and calmodulin-activated PDE1. This effect leads to an increase of cAMP over cGMP. It is mainly used as a pharmacological tool to implicate PDE1. Vinpocetine inhibits differently the various subtypes of PDE1 (IC50 from 8 to 50 μm) and it is also able to inhibit PDE7B. It can not be used as a specific tool to investigate the functional role of PDE1 due to its direct activator effects on BK (Ca) channels. Vinpocetine crosses the blood–brain barrier and is taken up by cerebral tissue. It has been hypothesized that vinpocetine can affect voltage-dependent calcium channels.