Regulation of inward rectifier K+ channels by shift of intracellular pH dependence

2004 ◽  
Vol 202 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Anthony Collins ◽  
Maureen Larson
Keyword(s):  
Intracellular Ph ◽  
Ph Dependence ◽  
Inward Rectifier ◽  
K Channels

scholarly journals K+ channels of stomatal guard cells. Characteristics of the inward rectifier and its control by pH.

1992 ◽  
Vol 99 (4) ◽  
pp. 615-644 ◽  
Author(s):  
M R Blatt
Keyword(s):  
Intracellular Ph ◽  
Guard Cells ◽  
Inward Rectifier ◽  
Equilibrium Potential ◽  
Egg Cell ◽  
K Channels ◽  
Inward Rectifiers ◽  
Stomatal Guard Cells ◽  
K Current ◽  
Current Reversal

Intracellular microelectrode recordings and a two-electrode voltage clamp have been used to characterize the current carried by inward rectifying K+ channels of stomatal guard cells from the broadbean, Vicia faba L. Superficially, the current displayed many features common to inward rectifiers of neuromuscular and egg cell membranes. In millimolar external K+ concentrations (Ko+), it activated on hyperpolarization with half-times of 100-200 ms, showed no evidence of time- or voltage-dependent inactivation, and deactivated rapidly (tau approximately 10 ms) on clamping to 0 mV. Steady-state conductance-voltage characteristics indicated an apparent gating charge of 1.3-1.6. Current reversal showed a Nernstian dependence on Ko+ over the range 3-30 mM, and the inward rectifier was found to be highly selective for K+ over other monovalent cations (K+ greater than Rb+ greater than Cs+ much greater than Na+). Unlike the inward rectifiers of animal membranes, the current was blocked by charybdotoxin and alpha-dendrotoxin (Kd much less than 50 nM), as well as by tetraethylammonium chloride (K1/2 = 9.1 mM); gating of the guard cell K+ current was fixed to voltages near -120 mV, independent of Ko+, and the current activated only with supramillimolar K+ outside (EK+ greater than -120 mV). Most striking, however, was inward rectifier sensitivity to [H+] with the K+ current activated reversibly by mild acid external pH. Current through the K+ inward rectifier was found to be largely independent of intracellular pH and the current reversal (equilibrium) potential was unaffected by pHo from 7.4 to 5.5. By contrast, current through the K+ outward rectifier previously characterized in these cells (1988. J. Membr. Biol. 102:235) was largely insensitive to pHo, but was blocked reversibly by acid-going intracellular pH. The action of pHo on the K+ inward rectifier could not be mimicked by extracellular Ca2+ for which changes in activation, deactivation, and conductance were consonant with an effect on surface charge ([Ca2+] less than or equal to 1 mM). Rather, extracellular pH affected activation and deactivation kinetics disproportionately, with acid-going pHo raising the K+ conductance and shifting the conductance-voltage profile positive-going along the voltage axis and into the physiological voltage range. Voltage and pH dependencies for gating were consistent with a single, titratable group (pKa approximately 7 at -200 mV) residing deep within the membrane electric field and accessible from the outside.(ABSTRACT TRUNCATED AT 400 WORDS)

Gating of inward-rectifier K+channels by intracellular pH

2000 ◽  
Vol 267 (19) ◽  
pp. 5837-5841 ◽  
Author(s):  
Uwe Schulte ◽  
Bernd Fakler
Keyword(s):  
Intracellular Ph ◽  
Inward Rectifier ◽  
K Channels

scholarly journals Small-molecule modulators of inward rectifier K+channels: recent advances and future possibilities

2010 ◽  
Vol 2 (5) ◽  
pp. 757-774 ◽  
Author(s):  
Gautam Bhave ◽  
Daniel Lonergan ◽  
Brian A Chauder ◽  
Jerod S Denton
Keyword(s):  
Small Molecule ◽  
Inward Rectifier ◽  
K Channels ◽  
Recent Advances ◽  
Small Molecule Modulators

CO2 inhibits specific inward rectifier K+ channels by decreases in intra- and extracellular pH

2000 ◽  
Vol 183 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Guoyun Zhu ◽  
Congxiao Liu ◽  
Zhiqiang Qu ◽  
Sengthong Chanchevalap ◽  
Haoxing Xu ◽  
...  
Keyword(s):  
Inward Rectifier ◽  
Extracellular Ph ◽  
K Channels

AMPA Receptor-Mediated Modulation of Inward Rectifier K+ Channels in Astrocytes of Mouse Hippocampus

2002 ◽  
Vol 19 (3) ◽  
pp. 447-458 ◽  
Author(s):  
Wolfgang Schröder ◽  
Gerald Seifert ◽  
Kerstin Hüttmann ◽  
Stefan Hinterkeuser ◽  
Christian Steinhäuser
Keyword(s):  
Ampa Receptor ◽  
Inward Rectifier ◽  
K Channels ◽  
Mouse Hippocampus

scholarly journals Polyamines as gating molecules of inward-rectifier K+channels

2000 ◽  
Vol 267 (19) ◽  
pp. 5824-5829 ◽  
Author(s):  
Dominik Oliver ◽  
Thomas Baukrowitz ◽  
Bernd Fakler
Keyword(s):  
Inward Rectifier ◽  
K Channels

Uterine Excitability and Ion Channels and Their Changes with Gestation and Hormonal Environment

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
Susan Wray ◽  
Sarah Arrowsmith
Keyword(s):  
Ion Channels ◽  
Inward Rectifier ◽  
Cation Channels ◽  
Annual Review ◽  
Publication Date ◽  
K Channels ◽  
Voltage Gated ◽  
New Findings ◽  
Voltage Dependent ◽  
Pore Domain

We address advances in the understanding of myometrial physiology, focusing on excitation and the effects of gestation on ion channels and their relevance to labor. This review moves through pioneering studies to exciting new findings. We begin with the myometrium and its myocytes and describe how excitation might initiate and spread in this myogenic smooth muscle. We then review each of the ion channels in the myometrium: L- and T-type Ca2+ channels, KATP (Kir6) channels, voltage-dependent K channels (Kv4, Kv7, and Kv11), twin-pore domain K channels (TASK, TREK), inward rectifier Kir7.1, Ca2+-activated K+ channels with large (KCNMA1, Slo1), small (KCNN1–3), and intermediate (KCNN4) conductance, Na-activated K channels (Slo2), voltage-gated (SCN) Na+ and Na+ leak channels, nonselective (NALCN) channels, the Na K-ATPase, and hyperpolarization-activated cation channels. We finish by assessing how three key hormones— oxytocin, estrogen, and progesterone—modulate and integrate excitability throughout gestation. Expected final online publication date for the Annual Review of Physiology, Volume 83 is February 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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