Myocardial uptake (rabbit) of six 99mTc-tagged pharmaceuticals and 85Sr after vasopressin-induced necrosis

A new rapid method for producing myocardial necrosis in rabbits was developed, using percutaneous intramyocardial injection of vasopressin in peanut oil. The 15-min procedure resulted in a mortality rate of 15% and a success rate among surviving animals of 50%. When the lesions were 24 hr old, strontium-85 and a technetium-99m-tagged agent were injected intravenously simultaneously, and the animals were killed 1,6, and 24 hr later for tissue radioassay. Strontium-85 failed to accumulate appreciably in the lesions. Three bone-seeking technetium complexes (pyrophosphate, methylene diphosphonate, and imidodiphosphonate) produced lesion-to-normal myocardial ratios of 6,5, and 14, respectively, at 1 hr, and 20,30, and 33 at 6 hr. The ratios for 99mTc-glucoheptonate were only 2 at 1 hr and 4 at 6 hr, while the ratios of 99mTc-acetylcysteine and 99mTc-citrate were even lower.