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Pharmacological evidence for a key role of voltage-gated $K^{+}$ channels in the function of rat aortic smooth muscle cells
| Content Provider | Scilit |
|---|---|
| Author | Tammaro, Paolo Smith, Amy L. Hutchings, Simon R. Smirnov, Sergey V. |
| Copyright Year | 2004 |
| Description | Journal: British Journal of Pharmacology The role of voltage-dependent (I(K(v))) and large conductance Ca(2+)-activated (BK(Ca)) K(+) currents in the function of the rat aorta was investigated using specific BK(Ca) and K(V) channel inhibitors in single rat aortic myocytes (RAMs) with patch-clamp technique and in endothelium-denuded aortic rings with isometric tension measurements. The whole-cell K(+) currents were recorded in RAMs dialysed with 200 and 444 nm Ca(2+) and in perforated-patch configuration. Electrophysiological analysis demonstrated that I(K(v)) appeared at >/=-40 mV, while BK(Ca) (isolated using 1 microm paxilline) were seen positive to -20 mV in all conditions. Voltage-dependent characteristics, but not maximal conductance, of I(K(v)) was significantly altered in increased [Ca(2+)](i). Correolide (1 microm) (a K(V)1 channel blocker) did not inhibit the I(K(v)), whereas millimolar concentration of TEA (IC(50)=3.1+/-0.6 mm, n=5) and 4-aminopyridine (4-AP, IC(50)=5.9+/-1.9 mm, n=7) suppressed I(K(v)). These results and immunocytochemical analysis suggest the K(V)2.1 channel to be a molecular correlate for I(K(v)). In nonstimulated aortic rings 1-5 mm TEA and 4-AP (inhibitors of I(K(v))), but not paxilline (1 microm), caused contraction. The frequency of contractile responses to TEA and 4-AP was increased in the presence of 10 mm KCl, which itself did not significantly affect the aortic basal tone. Phenylephrine (15-40 nm) induced sustained tension with superimposed slow oscillatory contractions (termed OWs). OWs were blocked by diltiazem, ryanodine and cyclopiazonic acid, suggesting the involvement of L-type Ca(2+) channels and ryanodine-sensitive Ca(2+) stores in this process. TEA and 4-AP, but not IbTX, paxilline or correolide, increased the duration and amplitude of OWs, indicating that I(K(v)) is involved in the control of oscillatory activity. In conclusion, our findings suggest that the K(V)2.1-mediated I(K(v)), and not BK(Ca), plays an important role in the regulation of the excitability and contractility of rat aorta. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1575342/pdf |
| Ending Page | 317 |
| Page Count | 15 |
| Starting Page | 303 |
| e-ISSN | 14765381 |
| DOI | 10.1038/sj.bjp.0705957 |
| Journal | British Journal of Pharmacology |
| Issue Number | 2 |
| Volume Number | 143 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 2004-09-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: British Journal of Pharmacology Vascular Smooth Muscle Cells Potassium Channels Single Smooth Muscle Cells Patch-clamp Technique Rhythmic Contraction Thoracic Aorta Ca2+-activated K+ Channels Voltage-gated K+ Channels Kv2.1 Channel |
| Content Type | Text |
| Resource Type | Article |
