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Smooth Muscle Ca 2+ ‐Activated and Voltage‐Gated K + Channels Modulate Conducted Dilation in Rat Isolated Small Mesenteric Arteries
Author(s) -
BELEZNAI TIMEA Z.,
YAROVA POLINA L.,
YUILL KATHRYN H.,
DORA KIM A.
Publication year - 2011
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1111/j.1549-8719.2011.00109.x
Subject(s) - hyperpolarization (physics) , dilation (metric space) , mesenteric arteries , phenylephrine , biophysics , vascular smooth muscle , chemistry , endothelium derived hyperpolarizing factor , gap junction , anatomy , artery , medicine , intracellular , biology , smooth muscle , biochemistry , stereochemistry , geometry , mathematics , nuclear magnetic resonance spectroscopy , blood pressure
Please cite this paper as: Beleznai, Yarova, Yuill and Dora (2011). Smooth Muscle Ca 2+ ‐Activated and Voltage‐Gated K + Channels Modulate Conducted Dilation in Rat Isolated Small Mesenteric Arteries. Microcirculation 18 ( 6 ), 487–500. Abstract Objective: To assess the influence of blocking smooth muscle large conductance Ca 2+ ‐activated K + channels and voltage‐gated K + channels on the conducted dilation to ACh and isoproterenol. Materials and Methods: Rat mesenteric arteries were isolated with a bifurcation, triple‐cannulated, pressurized and imaged using confocal microscopy. Phenylephrine was added to the superfusate to generate tone, and agonists perfused into a sidebranch to evoke local dilation and subsequent conducted dilation into the feed artery. Results: Both ACh− and isoproterenol‐stimulated local and conducted dilation with similar magnitudes of decay with distance along the feed artery (2000 μm: ∼15% maximum dilation). The gap junction uncoupler carbenoxolone prevented both conducted dilation and intercellular spread of dye through gap junctions. IbTx, TEA or 4‐AP, blockers of large conductance Ca 2+ ‐activated K + channels and voltage‐gated K + channels, did not affect conducted dilation to either agonist. A combination of either IbTx or TEA with 4‐AP markedly improved the extent of conducted dilation to both agonists (2000 μm: >50% maximum dilation). The enhanced conducted dilation was reflected in the hyperpolarization to ACh (2000 μm: Control, 4 ± 1 mV, n = 3; TEA with 4‐AP, 14 ± 3mV, n = 4), and was dependent on the endothelium. Conclusions: These data show that activated BK Ca and K V ‐channels serve to reduce the effectiveness of conducted dilation.