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SINGLE-CHANNEL AND WHOLE-CELL K-CURRENTS EVOKED BY LEVCROMAKALIM IN SMOOTH-MUSCLE CELLS FROM THE RABBIT PORTAL-VEIN

Beech, DJ; Zhang, H; Nakao, K; Bolton, TB (1993) SINGLE-CHANNEL AND WHOLE-CELL K-CURRENTS EVOKED BY LEVCROMAKALIM IN SMOOTH-MUSCLE CELLS FROM THE RABBIT PORTAL-VEIN. BRITISH JOURNAL OF PHARMACOLOGY, 110 (2). 583 - 590 (8). ISSN 0007-1188 10.1111/j.1476-5381.1993.tb13850.x
SGUL Authors: Bolton, Thomas Bruce

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Abstract

1. Single channel and whole-cell current recordings were made from single smooth muscle cells isolated from the rabbit portal vein. 2. Application of 10 microM levcromakalim ((-)-Ckm) to single cells held with pipettes containing 1 mM GDP induced a K-current (IK(Ckm)) which occurred in addition to the current caused by GDP alone (IK(GDP)) and averaged 135 pA at -37 mV. We have investigated whether the same K channels underlie the GDP- and Ckm-induced K-currents. 3. If 1 mM GDP was in the pipette but Mg ions were omitted the effect of GDP was absent and IK(Ckm) averaged only 10 pA, suggesting that the action of (-)-Ckm was Mg-dependent. 4. Intracellular ATP was not observed to have much effect on IK(-Ckm). Loading of cells with 10 mM ATP from the recording pipette had no significant effect and flash photolysis of caged-ATP loaded into cells from the pipette, estimated to release about 1 mM free ATP, also had no effect on IK(-Ckm). 5. Bath-applied glibenclamide inhibited IK(-Ckm) with an IC50 of 200 nM, a value 8 times higher than that found for inhibition of IK(GDP). The delayed rectifier K-current (IK(DR)) was also inhibited by glibenclamide but at higher concentrations (IC50 100 microM). Bath-applied tetraethylammonium ions (TEA) inhibited IK(-Ckm) and IK(GDP) to the same extent (IC50 about 7 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Item Type: Article
Additional Information: PubMed ID: 8242233
Keywords: Adenosine Triphosphate, Animals, Benzopyrans, Cromakalim, Glyburide, Guanosine Diphosphate, Magnesium, Muscle, Smooth, Vascular, Portal Vein, Potassium Channels, Pyrroles, Rabbits, Tetraethylammonium Compounds, Vasodilator Agents, Science & Technology, Life Sciences & Biomedicine, Pharmacology & Pharmacy, SMOOTH MUSCLE, LEVCROMAKALIM, K-CHANNEL, POTASSIUM CHANNEL, MESENTERIC-ARTERY, CORONARY-ARTERY, ATP, CROMAKALIM, INHIBITION, LEMAKALIM, BRL-38227, GLIBENCLAMIDE, CONDUCTANCE, SMOOTH MUSCLE, LEVCROMAKALIM, K-CHANNEL
Journal or Publication Title: BRITISH JOURNAL OF PHARMACOLOGY
ISSN: 0007-1188
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Dates:
DateEvent
1 October 1993Published
Web of Science ID: WOS:A1993LY79100011
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URI: http://openaccess.sgul.ac.uk/id/eprint/21
Publisher's version: 10.1111/j.1476-5381.1993.tb13850.x

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