Ca(2+)-activated K+ channels regulate action potential repolarization in urinary bladder smooth muscle

1997 ◽  
Vol 273 (1) ◽  
pp. C110-C117 ◽  
Author(s):  
T. J. Heppner ◽  
A. D. Bonev ◽  
M. T. Nelson
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Action Potential ◽  
Single Channel ◽  
Resting Membrane Potential ◽  
Channel Blockers ◽  
Bladder Smooth Muscle ◽  
Apparent Dissociation Constant ◽  
K Channels ◽  
Urinary Bladder Smooth Muscle

The goal of this study was to examine the role of large conductance Ca(2+)-activated K+ channels in the regulation of cell excitability in urinary bladder smooth muscle from the guinea pig. Ca(2+)-activated K+ channels were studied with single-channel recording techniques and found to be intracellular Ca2+ and voltage dependent and sensitive to external tetraethylammonium and blocked by nanomolar concentrations of iberiotoxin (apparent dissociation constant of 4 nM). Spontaneous action potentials recorded from intact tissue strips depended on external Ca2+ and were inhibited by Ca2+ channel blockers. Iberiotoxin (100 nM) significantly altered the configuration of the action potential by increasing the duration and peak amplitude of the action potential and decreasing the rate of decay. Iberiotoxin also increased the action potential frequency from 0.11 to 0.29 Hz. This study suggests that Ca(2+)-activated K+ channels play a significant role in the repolarization of the action potential and in the maintenance of the resting membrane potential of the urinary bladder smooth muscle.

scholarly journals Voltage-gated K+ channels sensitive to stromatoxin-1 regulate myogenic and neurogenic contractions of rat urinary bladder smooth muscle

2010 ◽  
Vol 299 (1) ◽  
pp. R177-R184 ◽  
Author(s):  
Muyan Chen ◽  
Whitney F. Kellett ◽  
Georgi V. Petkov
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Electrical Field Stimulation ◽  
Resting Membrane Potential ◽  
Bladder Smooth Muscle ◽  
Membrane Excitability ◽  
Molecular Fingerprints ◽  
Rat Urinary Bladder ◽  
Voltage Gated ◽  
Urinary Bladder Smooth Muscle

Members of the voltage-gated K+ (KV) channel family are suggested to control the resting membrane potential and the repolarization phase of the action potential in urinary bladder smooth muscle (UBSM). Recent studies report that stromatoxin-1, a peptide isolated from tarantulas, selectively inhibits KV2.1, KV2.2, KV4.2, and KV2.1/9.3 channels. The objective of this study was to investigate whether KV channels sensitive to stromatoxin-1 participate in the regulation of rat UBSM contractility and to identify their molecular fingerprints. Stromatoxin-1 (100 nM) increased the spontaneous phasic contraction amplitude, muscle force, and tone in isolated UBSM strips. However, stromatoxin-1 (100 nM) had no effect on the UBSM contractions induced by depolarizing agents such as KCl (20 mM) or carbachol (1 μM). This indicates that, under conditions of sustained membrane depolarization, the KV channels sensitive to stromatoxin-1 have no further contribution to the membrane excitability and contractility. Stromatoxin-1 (100 nM) increased the amplitude of the electrical field stimulation-induced contractions, suggesting also a role for these channels in neurogenic contractions. RT-PCR experiments on freshly isolated UBSM cells showed mRNA expression of KV2.1, KV2.2, and KV9.3, but not KV4.2 channel subunits. Protein expression of KV2.1 and KV2.2 channels was detected using Western blot and was further confirmed by immunocytochemical detection in freshly isolated UBSM cells. These novel findings indicate that KV2.1 and KV2.2, but not KV4.2, channel subunits are expressed in rat UBSM and play a key role in opposing both myogenic and neurogenic UBSM contractions.

Functional Characterization of Adenosine Receptors and Coupling to ATP-Sensitive K+ Channels in Guinea Pig Urinary Bladder Smooth Muscle

2002 ◽  
Vol 300 (3) ◽  
pp. 910-917 ◽  
Author(s):  
Sujatha M. Gopalakrishnan ◽  
Steven A. Buckner ◽  
Ivan Milicic ◽  
Duncan R. Groebe ◽  
Kristi L. Whiteaker ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Guinea Pig ◽  
Adenosine Receptors ◽  
Functional Characterization ◽  
Bladder Smooth Muscle ◽  
K Channels ◽  
Urinary Bladder Smooth Muscle

scholarly journals SK4 Encodes Intermediate Conductance Ca2+-Activated K+ Channels in Mouse Urinary Bladder Smooth Muscle Cells

2000 ◽  
Vol 84 (1) ◽  
pp. 97-100 ◽  
Author(s):  
Susumu Ohya ◽  
Shunichi Kimura ◽  
Mika Kitsukawa ◽  
Katsuhiko Muraki ◽  
Minoru Watanabe ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Bladder Smooth Muscle ◽  
K Channels ◽  
Urinary Bladder Smooth Muscle

EVIDENCE FOR THE PRESENCE OF LARGE CONDUCTANCE CA 2+ -ACTIVATED K + CHANNELS IN NATIVE HUMAN URINARY BLADDER SMOOTH MUSCLE

2008 ◽  
Vol 179 (4S) ◽  
pp. 129-129 ◽  
Author(s):  
Kiril L Hristov ◽  
Xiangli Cui ◽  
Whitney F Kellett ◽  
Eric Rovner ◽  
Georgi Petkov
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Bladder Smooth Muscle ◽  
K Channels ◽  
Human Urinary Bladder ◽  
Urinary Bladder Smooth Muscle

scholarly journals IBMX Relaxes Guinea Pig Urinary Bladder Smooth Muscle via Activation of Large Conductance Ca2+-Activated K+ Channels

2012 ◽  
Vol 102 (3) ◽  
pp. 689a
Author(s):  
Wenkuan Xin ◽  
Qiuping Cheng ◽  
Rupal P. Soder ◽  
Georgi V. Petkov
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Guinea Pig ◽  
Bladder Smooth Muscle ◽  
K Channels ◽  
Urinary Bladder Smooth Muscle
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