Iodine in rat alveolar macrophages following amiodarone treatment: quantitative X-ray microanalysis

The techniques of cryomicrotomy and X-ray microanalysis were used to quantitatively measure the subcellular distribution of iodine in rat alveolar macrophages following a single administration of the iodine-containing antiarrhythmic drug, amiodarone. When frozen, dried sections were analyzed, small amounts of iodine were found throughout the alveolar macrophages, but the major accumulations were observed in amorphous bodies and dense granules. The highest to lowest accumulation is in the following order: amorphous bodies (90 mmole I/kg dry wt) greater than dense granules (50 mmole I/kg dry wt) greater than nucleus = cytosol (10 mmoles I/kg dry wt). The amorphous bodies can contain high and low levels of iodine and the granules are found to have high and low levels of iron. Granules with the high and low levels of iron and amorphous bodies with the high and low levels of iodine can be found in the same cells. X-ray microanalysis proved useful in describing the intracellular distribution of iodine-labeled species following amiodarone administration.