Adenosine and guanosine 3',5'-cyclic monophosphate (cAMP and cGMP) are important ``second messengers'' involved in many physiological processes. BioVision's cGMP Direct Immunoassay Kit provides a direct competitive immunoassay for sensitive and quantitative determination of cGMP level in biological samples. The kit utilizes the recombinant Protein G coated plate to anchor cGMP polyclonal antibody. cGMP-HRP conjugates directly competes with cGMP from samples for binding to the cGMP specific antibody on the plate. After incubation and washing, the amount of cGMP-HRP bound to plate can easily be determined by reading OD450 nm. The intensity of OD450 nm is inversely proportional to the concentration of cGMP in samples. The kit provides a new acet