Estudio ultraestructural de la mionecrosis inducida en raton por el veneno de terciopelo (Bothrops asper) de Costa Rica

Abstract

Skeletal muscle from white mice was examined one and three hr after i.m. injection of 50 μg of Bothrops asper venom. At the light microscopic level we observed nectoric fibers with myolitic appearance, as early as the first hr and more marked by the third hr. At the ultrastructural level three kinds of fibers were observed: (a) fibers with normal morphology, (b) fibers with slight alteration at the sarcoplasmic reticulum and (c) fibers with strong alterations in several organelles; in these fibers, the main pathological feature was the disruption of myofibril architecture. This disruption started with the disappearance of A, H, I and M bands, followed by the alteration of Z line. At the end of this process an amorphous mass of proteins was observed. Shortly following envenomation, sarcoplasmic reticulum showed moderate dilatation and proliferation, but when degenerative changes were more evident, smaller and more abundant vacuoles were seen. Also, the plasma membrane was altered and disrupted in some fibers, whereas many mitochondria showed a swollen appearance and, in some cells, they were disrupted. An amorphous extracellular material was also observed as a consequence of envenomation. It is proposed that the ultrastructural basis of the muscular necrosis induced by terciopelo venom is the disruption and severe alteration of the myofibril architecture.