title: Ultrastructural alterations in the atrial myocardium of pigs with acute monensin toxicosis.
abstract: Monensin, A Na+-selective carboxylic ionophore, produces left atrial damage in pigs given toxic doses. Eight weanling pigs were given mycelial monensin orally (40 mg/kg body weight) and were killed on days 1, 2, 4, and 16 (two animals at each time interval) for ultrastructural study of the left atrial lesions. On days 1-4, extensive necrosis with contraction bands was present. Rapid macrophagic invasion and phagocytosis of sarcoplasmic debris was seen on days 2 and 4. Missing necrotic myocytes were outlined by persistent "tubes" of external laminas. In some surviving myocytes, sublethal injury was evident on day 1 by mitochondria with condensed conformation and on days 2, 4, and 16 by moderate to marked myofibrillar lysis and sarcoplasmic vacuolation. Monensin cardiotoxicity in pigs constitutes a unique example of selective injury to atrial myocardium.
mesh_terms: D000208:Acute Disease; D000818:Animals; D009202:Cardiomyopathies / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005260:Female; D005663:Furans / Q000633:toxicity*; D006325:Heart Atria / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D008264:Macrophages / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008985:Monensin / Q000633:toxicity*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000473:pathology / Q000648:ultrastructure*; D009336:Necrosis; D013552:Swine
chemical_list: D005663:Furans; D008985:Monensin