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Small‐ and Intermediate‐Conductance Calcium‐Activated K$ ^{+}$ Channels Provide Different Facets of Endothelium‐Dependent Hyperpolarization in Rat Mesenteric Artery
| Content Provider | Scilit |
|---|---|
| Author | Crane, G. J. Gallagher, N. Dora, K. A. Garland, C. J. |
| Copyright Year | 2003 |
| Description | Journal: The Journal of physiology Activation of both small-conductance $(SK_{Ca}$) and intermediate-conductance $(IK_{Ca}$) $Ca^{2+}$-activated $K^{+}$ channels in endothelial cells leads to vascular smooth muscle hyperpolarization and relaxation in rat mesenteric arteries. The contribution that each endothelial $K^{+}$ channel type makes to the smooth muscle hyperpolarization is unknown. In the presence of a nitric oxide (NO) synthase inhibitor, ACh evoked endothelium and concentration-dependent smooth muscle hyperpolarization, increasing the resting potential (approx. −53 mV) by around 20 mV at 3 μm. Similar hyperpolarization was evoked with cyclopiazonic acid (10 μm, an inhibitor of sarcoplasmic endoplasmic reticulum calcium ATPase (SERCA)) while 1-EBIO (300 μm, an $IK_{Ca}$ activator) only increased the potential by a few millivolts. Hyperpolarization in response to either ACh or CPA was abolished with apamin (50 nm, an $SK_{Ca}$ blocker) but was unaltered by 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (1 μm TRAM-34, an $IK_{Ca}$ blocker). During depolarization and contraction in response to phenylephrine (PE), ACh still increased the membrane potential to around −70 mV, but with apamin present the membrane potential only increased just beyond the original resting potential (circa−58 mV). TRAM-34 alone did not affect hyperpolarization to ACh but, in combination with apamin, ACh-evoked hyperpolarization was completely abolished. These data suggest that true endothelium-dependent hyperpolarization of smooth muscle cells in response to ACh is attributable to $SK_{Ca}$ channels, whereas $IK_{Ca}$ channels play an important role during the ACh-mediated repolarization phase only observed following depolarization. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2343487/pdf |
| Ending Page | 189 |
| Page Count | 7 |
| Starting Page | 183 |
| ISSN | 00223751 |
| e-ISSN | 14697793 |
| DOI | 10.1113/jphysiol.2003.051896 |
| Journal | The Journal of physiology |
| Issue Number | 1 |
| Volume Number | 553 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 2003-11-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: The Journal of physiology Smooth Muscle Hyperpolarization Dependent Hyperpolarization Resting Potential Ach Evoked Hyperpolarization Was Evoked |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physiology Sports Science |
