We have developed a double monoclonal sandwich enzyme immunoassay to m
easure smooth muscle myosin heavy chain (MHC). Analytical performance
of the assay showed reliable detection of smooth muscle MHC in human s
era. The mean of the smooth muscle MHC level in normal human sera was
0.9 +/- 0.9 ng/ml. In sera of patients with aortic dissection, the smo
oth muscle MHC level sharply elevated at the onset and rapidly decreas
ed to normal levels. Immunoassay of smooth muscle MHC in serum is a pr
omising method for biochemical diagnosis of smooth muscle disorders.