Summary
Alkalinization of the matrix side of the mitochondrial inner membrane by pH shifts from 6.8 to 8.3 caused a reversible increase in current of 3.2±0.2 pA (mean±se,n=21) at±40 mV measured using patch-clamp techniques. The current increase was reversed in a graded fashion by the addition of Mg2+ in 0.15m KCl corresponds to approximately 15 pS. Reversal potentials derived from whole patch currents indicated that the inner mitochondrial membrane was primarily cation selective at pH 6.8 with aP k/P Cl=32 (n=6). Treatment with alkaline pH (8.3) increased the current and anion permeability (P K/P Cl=16,n=6). The membrane becomes completely cation selective when low concentrations (12 μm) of the drug propranolol are added. The amphiphilic drugs amiodarone (4 μm), propranolol (70 μm) and quinine (0.6mm) blocked almost all of the current. The pH-dependent current was also inhibited by tributyltin. These results are consistent with the presence of two pathways in the inner mitochondrial membrane. One is cation selective and generally open and the other is anion selective and induced by alkaline pH. The alkaline pH-activated channel likely corresponds to the inner membrane anion channel postulated by others from suspension studies.
Similar content being viewed by others
References
Antonenko, Yu.N., Kinnally, K.W., Perini, S., Tedeschi, H. 1991. Selective effect of inhibitors on inner mitochondrial membrane channels.FEBS Lett 285:89–93
Beavis A.D. 1989. On the inhibition of the mitochondrial inner membrane anion uniporter by cationic amphiphiles and other drugs.J. Biol. Chem. 264:1508–1515
Beavis, A.D., Garlid, K.D. 1987. The mitochondrial inner membrane channel, regulation by divalent cations and protons.J. Biol. Chem. 262:15085–15093
Beavis, A.D., Garlid, K.D. 1988. Inhibition of the mitochondrial inner membrane anion channel by dicyclohexylcarbodiimide.J. Biol. Chem. 263:7574–7580
Beavis, A.D., Powers, M.F. 1989. The regulation of the mitochondrial inner membrane anion channel by magnesium and protons.J. Biol. Chem. 264:17148–17155
Bowman, C.L., Tedeschi, H. 1983. Kinetics of Lucifer Yellow CH efflux in giant mitochondria.Biochim. Biophys. Acta 731:261–266
Decker, G.L., Greenawalt, J.W. 1977. Ultrastructural and biochemical studies of mitoplasts and outer membranes derived from French-pressed mitochondria.J. Ultrastr. Res. 59:44–56
Garlid, K.D., Beavis, A.D. 1986. Evidence for the existence of an inner membrane anion channel in mitochondria.Biochim. Biophys. Acta 853:187–204
Hille B 1984. Ionic Channels and Excitable membranes. Sinauer Associates, Sunderland, MA
Kinnally, K.W., Campo, M.L., Tedeschi, H. 1989. Mitochondrial channel activity studied by patch clamping mitoplasts.J. Bioenerg. Biomembr. 21:497–506
Moran, O., Sandri, G., Panfili E., Stühmer, W., Sorgato, M.C. 1990. Electrophysiological characterization of contact sites in brain mitochondria.J. Biol. Chem. 265:908–913
Petronilli, V., Szabò, I., Zoratti, M. 1989. The inner mitochondrial membrane contains ion-conducting channels similar to those found in bacteria.FEBS Lett. 259:137–143
Powers, M.F., Beavis, A.D., 1991. Triorganotin compounds inhibit the mitochondrial inner membrane anion channel (IMAC).Biophys. J. 59:596a
Selwyn, M.J., Dawson, A.P., Fulton, D.V. 1979. An anion-conducting pore in the mitochondrial inner membraneBiochem. Soc. Trans. 7:216–219
Sorgato, M.C., Keller, B.U., Stühmer, W. 1987. Patch-clamping of the inner mitochondrial membrane reveals a voltage-dependent ion channel.Nature 330:498–500
Warhurst, I.W., Dawson, A.P., Selwyn, M.J. 1982. Inhibition of the electrogenic anion entry into rat liver mitochondria by N,N′-dicyclohexylcarbodiimide.FEBS Lett. 149:249–252
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Antonenko, Y.N., Kinnally, K.W. & Tedeschi, H. Identification of anion and cation pathways in the inner mitochondrial membrane by patch clamping of mouse liver mitoplasts. J. Membrain Biol. 124, 151–158 (1991). https://doi.org/10.1007/BF01870459
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01870459