Type

Journal Article

Authors

Mark A Hollywood
Keith D. Thornbury
Noel G McHale
Gerard P Sergeant
S Ohya
Eamonn Bradley
Barry Kyle

Subjects

Pharmacology

Topics
science urethra k channels v v action potentials smooth muscle cells current 3 subunit

Contribution of K v 2.1 channels to the delayed rectifier current in freshly dispersed smooth muscle cells from rabbit urethra (2011)

Abstract We have characterized the native voltage-dependent K + (K v ) current in rabbit urethral smooth muscle cells (RUSMC) and compared its pharmacological and biophysical properties with K v 2.1 and K v 2.2 channels cloned from the rabbit urethra and stably expressed in HEK 293 cells (HEK Kv2.1 and HEK Kv2.2 ). RUSMC were perfused with Hanks' solution at 37°C and studied using the patch clamp technique with K + -rich pipette solutions. Cells were bathed in 100 nM penitrem A (Pen A) to block large conductance Ca 2+ -activated K + (BK) currents and depolarized to +40 mV for 500 ms to evoke K v currents. These were unaffected by margatoxin, κ-dendrotoxin or α-dendrotoxin (100 nM, n=3-5), but were blocked by stromatoxin-1 (ScTx, IC 50 ~130 nM), consistent with the idea that the currents were carried through K v 2 channels. RNA was detected for K v 2.1 K v 2.2 and the silent subunit K v 9.3 in urethral smooth muscle. Immunocytochemistry showed membrane staining for both K v 2 subtypes and K v 9.3 in isolated RUSMC. HEK Kv2.1 and HEK Kv2.2 currents were blocked in a concentration dependent manner by ScTx with estimated IC 50 values of ~150 nM (K v 2.1, n=5) and 70 nM (K v 2.2, n=6). The mean V 1/2 of inactivation of the USMC K v current was – 56±3 mV (n=9). This was similar to the HEK Kv2.1 current (–55 ± 3 mV, n=13) but significantly different from the HEK Kv2.2 currents (-30 ± 3 mV, n=11). Action potentials (AP) evoked from RUSMC studied under current clamp mode were unaffected by ScTx. However when ScTx was applied in the presence of Pen A, the AP duration was significantly prolonged. Similarly, ScTx increased the amplitude of spontaneous contractions threefold, but only after Pen A application. These data suggest that K v 2.1 channels contribute significantly to the K v current in RUSMC.
Collections Ireland -> Dundalk IT -> Subject = Science
Ireland -> Dundalk IT -> Open Access DRIVERset
Ireland -> Dundalk IT -> Type = Article
Ireland -> Dundalk IT -> Status = Submitted

Full list of authors on original publication

Mark A Hollywood, Keith D. Thornbury, Noel G McHale, Gerard P Sergeant, S Ohya, Eamonn Bradley, Barry Kyle

Experts in our system

1
Mark A Hollywood
Dundalk IT
Total Publications: 35
 
2
Keith D. Thornbury
Dundalk IT
Total Publications: 27
 
3
Noel G McHale
Dundalk IT
Total Publications: 35
 
4
Gerard P Sergeant
Dundalk IT
Total Publications: 24