Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Opposite effects of pH on open-state probability and single channel conductance of kir4.1 channels.
Yang Z
,
Jiang C
.
???displayArticle.abstract???
1. A decrease in intracellular pH (pHi) inhibits whole-cell Kir4.1 currents. To understand channel biophysical properties underlying this inhibition, single channel Kir4.1 currents were studied in inside-out patches using symmetric concentrations of K+ applied to each side of the plasma membrane. Under such conditions, inward rectifying currents were observed in about 2 of 3 patches. At pH 7.4, these currents showed a single channel conductance of 22 pS with a channel open-state probability (Popen) of approximately 0.9. 2. The effects of intracellular protons on macroscopic Kir4.1 currents were examined in giant inside-out patches at various pH levels of internal solutions. Current amplitude increased with a modest acidification (pH 7.0 and 6.6), and decreased with further reductions in pHi. The Kir4.1 currents were completely suppressed at pH 5.4. These effects were fast and reversible. 3. Low pHi inhibited Popen and enhanced single channel conductance in a concentration-dependent manner with pK (midpoint pH value for channel inhibition) of 6.0 and 6.8, respectively. At pH 5.8, Popen was inhibited by 70 % and single channel conductance increased by 35 %. Washout brought both Popen and single channel conductance rapidly back to baseline levels. 4. Theoretical currents were calculated using percentage changes in Popen and single channel conductance at each pH level tested. The trajectory of these currents is very close to that of experimental currents recorded from giant patches. Thus, opposite effects of intracellular protons on Popen and single channel conductance are demonstrated, which are likely to result in changes of macroscopic Kir4.1 currents with low pH.
Bond,
Cloning and expression of a family of inward rectifier potassium channels.
1994, Pubmed,
Xenbase
Bond,
Cloning and expression of a family of inward rectifier potassium channels.
1994,
Pubmed
,
Xenbase
Bredt,
Cloning and expression of two brain-specific inwardly rectifying potassium channels.
1995,
Pubmed
,
Xenbase
Choe,
A conserved cytoplasmic region of ROMK modulates pH sensitivity, conductance, and gating.
1997,
Pubmed
,
Xenbase
Chuang,
Regulation of IRK3 inward rectifier K+ channel by m1 acetylcholine receptor and intracellular magnesium.
1997,
Pubmed
,
Xenbase
Cohen,
Binding of the inward rectifier K+ channel Kir 2.3 to PSD-95 is regulated by protein kinase A phosphorylation.
1996,
Pubmed
Cohen,
Inhibition of an inward rectifier potassium channel (Kir2.3) by G-protein betagamma subunits.
1996,
Pubmed
,
Xenbase
Coulter,
Identification and molecular localization of a pH-sensing domain for the inward rectifier potassium channel HIR.
1995,
Pubmed
,
Xenbase
Fakler,
Identification of a titratable lysine residue that determines sensitivity of kidney potassium channels (ROMK) to intracellular pH.
1996,
Pubmed
,
Xenbase
Henry,
Protein kinase C inhibition of cloned inward rectifier (HRK1/KIR2.3) K+ channels expressed in Xenopus oocytes.
1996,
Pubmed
,
Xenbase
Huang,
Direct activation of inward rectifier potassium channels by PIP2 and its stabilization by Gbetagamma.
1998,
Pubmed
,
Xenbase
Ito,
Intracellular protons inhibit inward rectifier K+ channel of guinea-pig ventricular cell membrane.
1992,
Pubmed
Jiang,
Oxygen deprivation activates an ATP-inhibitable K+ channel in substantia nigra neurons.
1994,
Pubmed
McNicholas,
pH-dependent modulation of the cloned renal K+ channel, ROMK.
1998,
Pubmed
,
Xenbase
Nichols,
Inward rectifier potassium channels.
1997,
Pubmed
Pearson,
Expression of a functional Kir4 family inward rectifier K+ channel from a gene cloned from mouse liver.
1999,
Pubmed
,
Xenbase
Pessia,
Subunit positional effects revealed by novel heteromeric inwardly rectifying K+ channels.
1996,
Pubmed
,
Xenbase
Pineda,
Carbon dioxide regulates the tonic activity of locus coeruleus neurons by modulating a proton- and polyamine-sensitive inward rectifier potassium current.
1997,
Pubmed
Qu,
Identification of a critical motif responsible for gating of Kir2.3 channel by intracellular protons.
1999,
Pubmed
,
Xenbase
Schlatter,
pH dependence of K+ conductances of rat cortical collecting duct principal cells.
1994,
Pubmed
Schulte,
pH-dependent gating of ROMK (Kir1.1) channels involves conformational changes in both N and C termini.
1998,
Pubmed
,
Xenbase
Shuck,
Cloning and characterization of two K+ inward rectifier (Kir) 1.1 potassium channel homologs from human kidney (Kir1.2 and Kir1.3).
1997,
Pubmed
,
Xenbase
Tsai,
Intracellular H+ inhibits a cloned rat kidney outer medulla K+ channel expressed in Xenopus oocytes.
1995,
Pubmed
,
Xenbase
Wang,
Regulation of small-conductance K+ channel in apical membrane of rat cortical collecting tubule.
1990,
Pubmed
Zhou,
Stimulation of total CO2 flux by 10% CO2 in rabbit CCD: role of an apical Sch-28080- and Ba-sensitive mechanism.
1994,
Pubmed
Zhu,
Effects of intra- and extracellular acidifications on single channel Kir2.3 currents.
1999,
Pubmed
,
Xenbase
