An enzyme-linked immunosorbent assay (ELISA) for guanosine 3',5'-cyclic monophosphate (cGMP) in human plasma and urine using monoclonal antibody.

An ELISA for cGMP in human plasma and urine using a monoclonal antibody is described. The monoclonal antibody was raised against succinyl cGMP conjugated to human serum albumin. The conjugate was adsorbed to the ELISA plate, giving an immobilized antigen approach which simplifies subsequent assay procedures. As low as 1.56 fmol/well of both plasma and urinary cGMP is measurable. Recoveries of added cGMP in plasma and urine were from 97% to 105%. Intra-assay coefficients of variation were less than 7.0% for plasma and 7.1% for urine samples. Inter-assay coefficients of variation for plasma and urine samples were less than 9.9% and 9.5%, respectively. The values obtained by ELISA correlated well with those by radioimmunoassay (RIA) (plasma: r = 0.96, n = 50; urine: r = 0.98, n = 60).