title: Ultrastructural observations in ponies after treatment with monensin.
abstract: Ultrastructural studies were made of myocardium, diaphragm, appendicular muscle, liver, and kidney of 3 ponies acutely poisoned with a single oral dose of monensin (4 mg/kg of body weight). These ponies developed severe signs of toxicosis and were killed 28 to 72 hours after treatment. Severe mitochondrial damage (swelling) and lipoidosis in myocardial tissues were observed in 2 of the 3 ponies; similar, but less severe, changes were observed in the 3rd pony. The hepatocytes of the 3 ponies were characterized by increased amounts of smooth endoplasmic reticulum, large numbers of lipid droplets, vacuoles bounded by fibrous material, and a 2-fold increase in the number of peroxisomes per cell. Some hepatocytes also contained a membrane-bounded protein-like body. The observations indicate that heart mitochondria are primary targets of monensin poisoning in ponies.
mesh_terms: D000818:Animals; D005260:Female; D005663:Furans / Q000506:poisoning*; D006734:Horse Diseases / Q000473:pathology*; D006736:Horses; D008099:Liver / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D008985:Monensin / Q000506:poisoning*; D009206:Myocardium / Q000648:ultrastructure
chemical_list: D005663:Furans; D008985:Monensin