title: Inner mitochondrial membrane anion channel is present in brown adipocytes but is not identical with the uncoupling protein.
abstract: Vesicles of inner mitochondrial membrane, mitoplasts, from rat brown adipose tissue were prepared by osmotic swelling and studied using the patch-clamp technique. Current events of a 107.8 +/- 8.7 pS (n = 16, 21 degrees C) channel were recorded in the mitoplast-attached mode. This channel was selective for anions and its kinetics resembled those of channels previously found in liver and heart mitochondria of mouse and ox. In whole-mitoplast mode each of five purine nucleotides (20 microM) blocked the channel. This is the first demonstration of pharmacological blockade of this type of channel. Although a similar anion channel in mouse and ox mitochondria was suggested to be the uncoupling protein (UCP) associated with nonshivering thermogenesis, we present several arguments against this possibility. Thus we describe a high-conductance, purine-nucleotide-binding, anion selective mitochondrial channel, that is not the UCP.
authors.affiliation: Physiologisches Institut, Justus-Liebig-Universität, Federal Republic of Germany.
authors.forename: T
authors.initials: T
authors.lastname: Klitsch
authors.forename: D
authors.initials: D
authors.lastname: Siemen
mesh_terms: D002001:Adipose Tissue, Brown / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D000818:Animals; D002352:Carrier Proteins; D002712:Chlorides / Q000378:metabolism*; D004553:Electric Conductivity / Q000187:drug effects / Q000502:physiology; D007425:Intracellular Membranes / Q000502:physiology / Q000648:ultrastructure*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D008565:Membrane Proteins / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology / Q000648:ultrastructure*; D024101:Mitochondrial Proteins; D011685:Purine Nucleotides / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D000071256:Uncoupling Protein 1
chemical_list: D002352:Carrier Proteins; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011685:Purine Nucleotides; D000071256:Uncoupling Protein 1