Inhibiting PDE9 reduces the degradation of cyclic GMP
which is critical to signal transmission among cells.
Francis, "Cyclic GMP
phosphodiesterase-5: target of sildenafil, " Journal of Biological Chemistry, vol.
Ulmer, "The antagonistic action of cyclic GMP
and cyclic AMP on proliferation of B and T lymphocytes," Immunology, vol.
The cyclic nucleotide hydrolytic activity assay was carried out using a radioenzymatic method as previously described (Keravis et al., 2005) at a substrate concentration of either 1 [micro]M cyclic AMP or 1 [micro]M cyclic GMP
in presence of 10.000 cpm [[sup.3]H]-cyclic AMP or [[sup.3]H]-cyclic GMP as a tracer.
Cardiac tissue cyclic GMP
levels were measured by an enzyme immunoassay test-system (R&D Systems, Inc.
Effects of two selective phosphodiesterase type 5 inhibitors, sildenafil and vardenafil, on object recognition memory and hippocampal cyclic GMP
levels in the rat.
(7, 8) Nitric oxide triggers the synthesis of cyclic GMP
which causes calcium uptake leading to muscle cell relaxation, vasodilation and increased blood flow to the penis.
According to the research, this is because sildenafil inhibits the breakdown of cyclic GMP
, which has been well known as a messenger molecule used by the body to control blood pressure and flow, and has now been shown to play an important role determining which type of fat-white or brown-the body stores.
Erections occur when a stimulus triggers the release of nitric oxide, which activates an enzyme--cyclic guano-sine monophosphate (cyclic GMP
)--that causes the smooth muscle of the penis to relax and blood flow to increase.
The pharmacological and physiological role of cyclic GMP
in vascular smooth muscle relaxation.Ann Rev Pharmacol Toxicol.
production can be catalyzed by plasma-membrane-receptor guanylyl cyclases or by soluble, cytosolic guanylyl cyclases (Wong and Garbers, 1992; Schmidt et al., 1993; Giannella, 1995).
PDE is a generic term referring to at least 11 distinct families that have been identified as hydrolyzing cAMP or cyclic guanosine 3',5' -monophosphate (cyclic GMP
, or cGMP) and that have unique tissue and subcellular distributions.