Mushroom poisoning due to Cortinarius speciosissimus: electron microscope study in rats.

The effects of a poisonous mushroom, Cortinarius speciosissimus, on rat kidney were studied by transmission electron microscopy. Suspension of dried mushroom (500 mg/kg body weight) was administered as a single dose directly into the esophagus. The kidneys were fixed by perfusion, and both cortex and medulla were sampled. C. speciosissimus toxin acted primarily on the epithelial cells of the proximal tubules. No changes were seen in the glomeruli. First ultrastructural changes were observed at 2 days in the renal cortex. The most prominent damage occurred at 5 days, when most of the proximal tubular cells appeared necrotic. Dark bodies (diameter 0.15-0.5 micron) spaced by 25-45 nm were frequently found in the damaged tubular cell nuclei. Regeneration of the tubular cells was seen at 10 days. After 2 months, increased amount of collagen fibres were seen between tubules. The nuclear changes in the damaged tubular cells and the slowly manifesting toxicity suggest that C. speciosissimus toxin acts on nuclei or nucleoli and/or metabolic pathways associated with them.