Uptake of infarct-imaging agents in reversibly and irreversibly injured myocardium in cultured fetal mouse heart

Abstract

We studied the specificity of uptake of infarct-imaging agents for reversibly or irreversibly injured myocardium independently of blood flow by using intact beating fetal mouse hearts in organ culture. Reversible injury resulted from deprivation of oxygen and glucose for 4 hours at 37 degrees C; irreversible injury, from similar deprivation at 42 degrees C. At the end of the insult, uptake of 99mTc(Sc)-labeled pyrophosphate, glucoheptonate, or tetracycline was markedly increased in irreversibly damaged and, to a lesser degree, in reversibly injured hearts. After 24 hours of recovery, necrotic hearts accumulated even more pyrophosphate and tatracycline but less glucoheptonate. Uptake of radioiodinated tetracycline increased only in irreversibly injured hearts. Pyrophosphate uptake was not reduced in hearts cultured in calcium-free medium. These finding suggest that 99mTc(Sn)-labeled pyrophosphate, tetracycline, and glucoheptonate preferentially localize in irreversibly damaged myocardium; the 99mTc(Sn) complex modifies the specificity of uptake; and the uptake of 99mTc(Sn)-pyrophosphate appears unrelated to calcium uptake.