Localization of Tritiated Digoxin in Dog Myocardium by Electron Microscopic Autoradiography

Abstract

Five mongrel dogs were given 0.08 mg/kg of tritiated digoxin over a 24-hour period. Left ventricular myocardium was excised and subsequently fixed, dehydrated, and embedded in Epon 812 epoxy resin. Tissue was sectioned and coated with a monolayer of photographic nuclear emulsion and exposed for varying time intervals up to three months. After development these autoradiographs were viewed with the electron microscope. It was found that of the total number of nuclear tracks counted, 75% were found to overlie the sarcomere of the myofibril, 27% to overlie the mitochondria, and 8% to overlie other structures. Of those tracks associated with the sarcomere, 72% were found to overlie the A band. Evaluation of the data obtained and the techniques used are presented.