Iodine as a Tracer for Intracellular Drug Localization: X-Ray Microanalysis

Abstract

The antiarrhythmic drug, amiodarone. is a cationic amphiphilic compound which can cause cellular lipidosis and pulmonary toxicity. It contains two atoms of iodine per molecule. We have previosly reported our results on the use of x-ray microanalysis to quantitatively measure the subcellular distribution of iodine in rat alveolar macrophages following a single adminstration of the drug. We found small amounts of iodine throughout the alveolar macrophages. The major accumulations were observed in the lipid lamellar structures, which were of lysosomal origin and appeared as amorphous bodies in freeze-dried cryosection. More recently we have examined the effects of long-term treatment of one week and nine weeks with amiodarone. Severe lipidosis in the alveolar macrophages occurred after one week treatment with amiodarone (Fig.l). Substantial changes in iodine distribution occurred in cells with increasing length of drug treatment. In addition to the high concentrations of iodine in the lamellar bodies, the iodine levels in the nuclei slowly increased with the length of treatment, and after 9 weeks of treatment, approached the high levels found in the lamellar bodies.