108-pS Channel in Brown Fat Mitochondria Might Be Identical to the Inner Membrane Anion Channel

• Published in: The Journal of biological chemistry 1997-08, Vol.272 (31), p.19282-19289
• Main Authors: Borecký, Jiřı́, Ježek, Petr, Siemen, Detlef
• Format: Article
• Language: English
• Subjects: ACTIVE TRANSPORT; Adipose Tissue, Brown - metabolism; ADIPOSE TISSUES; Animals; ANION; ANIONES; ANIONS; ANTIMETABOLITE; ANTIMETABOLITES; ANTIMETABOLITOS; BENZENETRICARBOXYLATES; CELL MEMBRANES; CHLORIDES; CHLORURE; CIBACHON BLUE 3GA; CLORUROS; CONDUCTIVIDAD ELECTRICA; CONDUCTIVITE ELECTRIQUE; Cricetinae; DRUGS; ELECTRIC CURRENT; ELECTRICAL CONDUCTIVITY; ELECTRICIDAD; ELECTRICITE; ELECTRICITY; ELECTROPHYSIOLOGY; FOSFATOS; GOLDEN HAMSTERS; HAMSTER; HAMSTERS; Hydrogen-Ion Concentration; INHIBICION; INHIBITION; Ion Channels - drug effects; Ion Channels - physiology; Male; MEDICAMENT; MEDICAMENTOS; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; MEMBRANE POTENTIAL; Mesocricetus; MITOCHONDRIA; Mitochondria - metabolism; MITOCHONDRIE; MITOCONDRIA; NIFEDIPINE; Nifedipine - pharmacology; NIGULDIPINE; ORGANIC ANIONS; PHOSPHATE; PHOSPHATES; PROPRANOLOL; Propranolol - pharmacology; PROTEINAS; PROTEINE; PROTEINS; SULFATE; SULFATOS; SULPHATES; SURFACE PROTEINS; TEJIDO ADIPOSO; TISSU ADIPEUX; Triazines - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)38955-5

Single-channel and whole-mitoplast patch-clamp recordings were employed to characterize the 108-pS (Cl−) channel in brown fat mitochondrial mitoplasts. We demonstrated the ability of this channel to conduct di- and trivalent anions, such as sulfate, phosphate, and benzenetricarboxylates, and its blockage by propranolol, 1,4-dihydropyridine-type Ca2+ antagonists, and Cibacron blue. Moreover, we have revealed its pH dependence for the first time. As a basis for the characteristic potential dependence of the whole-mitoplast current, we identified an open probability, increasing with depolarizing (positive) potentials, Eh, and being almost zero in the hyperpolarizing range. Events at negativeEh exhibit a short flickering behavior, whereas at positive Eh, they become much longer. This voltage dependence is influenced by pH in such a way that, at acidic pH, the 108-pS channel possesses a low open probability throughout the observed potential range, whereas at alkaline pH, the channel switches to long openings, even at a negative potential. All these properties lead us to conclude that the inner membrane anion channel, which has been characterized only by light scattering studies, and the 108-pS inner membrane channel, which has been characterized electrophysiologically, are one and the same process.