Monoclonal antibody (MAb) attained from hybridoma 1A5 was against human cardiac myosin heavy chains (CMHC) and didn’t react with smooth muscle. It was labeled with Na 125 I and injected to the rats suffered from acute myocardial necrosis, which were treated by isoproylarterenol. After injection, the rats were studied from the 4 th to the 48 th hours by relative radioactivity in blood, thyroid gland, stomach, liver, lung, muscle and heart, respectively. The results indicated that 125 I CMHC MAb could specifically reach the target necrotic organ in the 4 th hours (2 03±0 60 ) and remained up to the 48 th hours (2 55±0 49) or longer, at which the 8 th was higher (4 89±0 44). Meanwhile 125 I CMHC MAb showed much higher affinity to necrotic cardiac tissue than the normal ( P <0 001). The same results were should in the blood from 4 th (4 94±0 45) to 48 th (2 70±0 12). Thus 125 I CMHC MAb can be considered as an effective tool for image diagnosis of acute myocardial necrosis.
