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Properties and molecular basis of the mouse urinary bladder voltage-gated K+ current
Potassium channels play an important role in controlling the excitability of urinary bladder smooth muscle (UBSM). Here we describe the biophysical, pharmacological and molecular properties of the mouse UBSM voltage-gated K + current ( I K(V) ). The I K(V) activated, deactivated and inactivated slow...
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Published in: | The Journal of physiology 2003-05, Vol.549 (1), p.65-74 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Potassium channels play an important role in controlling the excitability of urinary bladder smooth muscle (UBSM). Here we
describe the biophysical, pharmacological and molecular properties of the mouse UBSM voltage-gated K + current ( I K(V) ). The I K(V) activated, deactivated and inactivated slowly with time constants of 29.9 ms at +30 mV, 131 ms at â40 mV and 3.4 s at +20
mV. The midpoints of steady-state activation and inactivation curves were 1.1 mV and â61.4 mV, respectively. These properties
suggest that I K(V) plays a role in regulating the resting membrane potential and contributes to the repolarization and after-hyperpolarization
phases of action potentials. The I K(V) was blocked by tetraethylammonium ions with an IC 50 of 5.2 m m and was unaffected by 1 m m 4-aminopyridine. RT-PCR for voltage-gated K + channel (K V ) subunits revealed the expression of Kv2.1, Kv5.1, Kv6.1, Kv6.2 and Kv6.3 in isolated UBSM myocytes. A comparison of the
biophysical properties of UBSM I K(V) with those reported for Kv2.1 and Kv5.1 and/or Kv6 heteromultimeric channels demonstrated a marked similarity. We propose
that heteromultimeric channel complexes composed of Kv2.1 and Kv5.1 and/or Kv6 subunits form the molecular basis of the mouse
UBSM I K(V) . |
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ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.2003.039859 |