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Expression and function of native potassium channel (K V α1) subunits in terminal arterioles of rabbit
- Source :
- The Journal of Physiology. 534:691-700
- Publication Year :
- 2001
- Publisher :
- Wiley, 2001.
-
Abstract
- 1. In this study we investigated the expression and function of the K(V)alpha1 subfamily of voltage-gated K(+) channels in terminal arterioles from rabbit cerebral circulation. 2. K(+) current was measured from smooth muscle cells within intact freshly isolated arteriolar fragments. Current activated on depolarisation positive of about -45 mV and a large fraction of this current was blocked by 3,4-diaminopyridine (3,4-DAP) or 4-aminopyridine (4-AP), inhibitors of K(V) channels. Expression of cRNA encoding K(V)1.6 in Xenopus oocytes also generated a 4-AP-sensitive K(+) current with a threshold for activation near -45 mV. 3. Immunofluorescence labelling revealed K(V)1.2 to be specifically localised to endothelial cells, and K(V)1.5 and K(V)1.6 to plasma membranes of smooth muscle cells. 4. K(V) channel current in arteriolar fragments was blocked by correolide (which is specific for the K(V)alpha1 family of K(V) channels) but was resistant to recombinant agitoxin-2 (rAgTX2; which inhibits K(V)1.6 but not K(V)1.5). Heterologously expressed K(V)2.1 was resistant to correolide, and K(V)1.6 was blocked by rAgTX2. 5. Arterioles that were mildly preconstricted and depolarised by 0.1-0.3 nM endothelin-1 constricted further in response to 3,4-DAP, 4-AP or correolide, but not to rAgTX2. 6. We suggest that K(V)alpha1 channels are expressed in smooth muscle cells of terminal arterioles, underlie a major part of the voltage-dependent K(+) current, and have a physiological function to oppose vasoconstriction. K(V)alpha1 complexes without K(V)1.5 appear to be uncommon.
- Subjects :
- Male
medicine.medical_specialty
Potassium Channels
Physiology
Xenopus
Scorpion Venoms
Muscle, Smooth, Vascular
Cell membrane
Kv1.5 Potassium Channel
Xenopus laevis
Cerebral circulation
Internal medicine
Kv1.2 Potassium Channel
Potassium Channel Blockers
medicine
Animals
Tissue Distribution
4-Aminopyridine
biology
Chemistry
Cell Membrane
Electric Conductivity
Potassium channel blocker
Depolarization
Original Articles
biology.organism_classification
Molecular biology
Triterpenes
Potassium channel
Arterioles
medicine.anatomical_structure
Endocrinology
Potassium Channels, Voltage-Gated
Cerebrovascular Circulation
Oocytes
Endothelium, Vascular
Rabbits
Amifampridine
medicine.symptom
Vasoconstriction
Delayed Rectifier Potassium Channels
medicine.drug
Subjects
Details
- ISSN :
- 14697793 and 00223751
- Volume :
- 534
- Database :
- OpenAIRE
- Journal :
- The Journal of Physiology
- Accession number :
- edsair.doi.dedup.....6e94f2279673e32fe0ca14ce54de81af