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- Title
Functional Expression Profile of Voltage-Gated K Channel Subunits in Rat Small Mesenteric Arteries.
- Authors
Cox, Robert; Fromme, Samantha
- Abstract
Multiple K channel complexes contribute to total K current in numerous cell types and usually subserve different physiological functions. Identifying the complete compliment of functional K channel subunits in cells is a prerequisite to understanding regulatory function. It was the goal of this work to determine the complete K subunit compliment that contribute to functional K currents in rat small mesenteric artery (SMA) myocytes as a prelude to studying channel regulation. Using RNA prepared from freshly dispersed myocytes, high levels of K 1.2, 1.5, and 2.1 and lower levels of K 7.4 α-subunit expressions were demonstrated by quantitative PCR and confirmed by Western blotting. Selective inhibitors correolide ( K 1; COR), stromatoxin ( K 2.1; ScTx), and linopirdine ( K 7.4; LINO) decreased K current at +40 mV in SMA by 46 ± 4, 48 ± 4, and 6.5 ± 2 %, respectively, and K current in SMA was insensitive to α-dendrotoxin. Contractions of SMA segments pretreated with 100 nmol/L phenylephrine were enhanced by 27 ± 3, 30 ± 8, and 7 ± 3 % of the response to 120 mmol/L KCl by COR, ScTX, and LINO, respectively. The presence of K 6.1, 9.3, β1.1, and β1.2 was demonstrated by RT-PCR using myocyte RNA with expressions of Kβ1.2 and K 9.3 about tenfold higher than Kβ1.1 and K 6.1, respectively. Selective inhibitors of K 1.3, 3.4, 4.1, and 4.3 channels also found at the RNA and/or protein level had no significant effect on K current or contraction. These results suggest that K current in rat SMA myocytes are dominated equally by two major components consisting of K 1.2-1.5-β1.2 and K 2.1-9.3 channels along with a smaller contribution from K 7.4 channels but differences in voltage dependence of activation allows all three to provide significant contributions to SMA function at physiological voltages.
- Subjects
ARTERIES; MESENTERIC artery; MUSCLE cells; POTASSIUM channels; WESTERN immunoblotting
- Publication
Cell Biochemistry & Biophysics, 2016, Vol 74, Issue 2, p263
- ISSN
1085-9195
- Publication type
Article
- DOI
10.1007/s12013-015-0715-4