title: Functional aspects of megamitochondria isolated from hydrazine- and ethanol-treated rat livers.
abstract: It is essential to analyze functions of megamitochondria (MG) to elucidate the mechanism of the formation of MG induced under various pathological conditions. The MG fraction obtained by a routine isolation procedure for normal mitochondria always consists of a mixed population of mitochondria enlarged to various degrees and also normal-sized ones. The purpose of the present study is to answer the question of whether or not data obtained from the MG fraction consisting of such a heterogeneous population of mitochondria with respect to their sizes really reflect functions of MG. In the present study mitochondria were obtained from the livers of rats treated with a 1% hydrazine diet for 8 days and those given 32% ethanol in drinking water for up to 2 months using various isolation procedures. Results obtained are summarized as follows: (i) mitochondria enlarged to various degrees and normal-sized ones are sometimes connected with each other by a narrow stalk in the hepatocyte of hydrazine-treated animals, and such connections are maintained to some extent when mitochondria are isolated; and (ii) mitochondria obtained from experimental animals by a routine isolation procedure for mitochondria ((700-7000)gR2"') and those obtained by alternative isolation procedure yielding the heavy ((500-2000)gR2"') and light ((2000-7000)gR2"') fractions show some functional similarities: decreases in the content of cytochrome a + a3; decreases in oxygen consumptions and phosphorylating abilities; decreases in monoamine oxidase and cytochrome c oxidase activities; lowered membrane potential of mitochondria; decreases in the rate of the generation of reactive oxygen species. These results may suggest that mitochondria enlarged to various degrees and normal-sized ones are functionally similar to each other and that the MG fraction obtained by a routine isolation procedure for normal mitochondria can be applied to the study of the function of MG.
authors.affiliation: Department of Cell Biology and Molecular Pathology, Nagoya University School of Medicine, Nagoya, Japan. twakaba@tsuru.med.nagoya-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Wakabayashi
authors.forename: M A
authors.initials: MA
authors.lastname: Teranishi
authors.forename: M
authors.initials: M
authors.lastname: Karbowski
authors.forename: Y
authors.initials: Y
authors.lastname: Nishizawa
authors.forename: J
authors.initials: J
authors.lastname: Usukura
authors.forename: C
authors.initials: C
authors.lastname: Kurono
authors.forename: T
authors.initials: T
authors.lastname: Soji
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D003576:Electron Transport Complex IV / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D005434:Flow Cytometry; D006834:Hydrazines / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008930:Mitochondria, Liver / Q000502:physiology* / Q000648:ultrastructure; D008995:Monoamine Oxidase / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species
chemical_list: D006834:Hydrazines; D017382:Reactive Oxygen Species; C029424:hydrazine; D000431:Ethanol; D008995:Monoamine Oxidase; D003576:Electron Transport Complex IV