Porphyrin Metabolism in Experimental Hepatic Siderosis in the Rat

S ummary . Rats previously rendered siderotic by intraperitoneal administration of iron‐dextran became porphyric much more rapidly than non‐siderotic animals when fed hexachlorobenzene. Fluorescence microscopy showed that initially porphyrin storage was focal and confined to the centrilobular zone but later became diffuse throughout the lobule. Analysis of liver extracts by thin layer chromatography revealed only 8‐ and 7‐carboxyl porphyrins which also predominated in the urine. The patterns resembled those seen in patients with symptomatic porphyria. These data are interpreted as further evidence that siderosis is an important factor in the derangement of hepatic haem biosynthesis which leads to the development of symptomatic porphyria.