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Release of nitric oxide is modulated by endothelial cell membrane potential in rat basilar artery
Author(s) -
Plane Frances,
Cole William
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1166-b
Subject(s) - apamin , hyperpolarization (physics) , chemistry , biophysics , membrane potential , endothelium , charybdotoxin , acetylcholine , depolarization , nitric oxide , potassium channel , endothelial stem cell , endocrinology , medicine , biochemistry , biology , in vitro , stereochemistry , nuclear magnetic resonance spectroscopy , organic chemistry
Endothelium‐dependent relaxation of isolated rat basilar artery to acetylcholine (ACh) is abolished by pre‐incubation with L‐N G ‐nitroarginine methyl ester (L‐NAME; 100 μM), an inhibitor of nitric oxide (NO) synthase, indicating that this responses can be fully accounted for by the release of endothelium‐derived NO. In the presence of L‐NAME, smooth muscle hyperpolarization to either ACh (10 μmoles) or 1‐ethyl‐2‐benzimidazolinone (EBIO; 10 μmoles), an activator of small‐ (SK Ca ) and intermediate‐calcium activated potassium (IK Ca ) channels, was abolished. Hyperpolarization of endothelial cell membrane potential to ACh was significantly inhibited by apamin (50 nM) an inhibitor of SK Ca channels whereas hyperpolarization to EBIO was significantly inhibited by pre‐incubation with TRAM‐34 (1 μM), an inhibitor of IK Ca channels. Hyperpolarization to both ACh and EBIO was abolished by the combination of TRAM‐34 and apamin. These inhibitors did not significantly alter the resting membrane potential of smooth muscle cells but caused significant depolarization of the endothelial cell membrane potential. It is concluded that endothelial cell hyperpolarization mediated by activation of calcium‐activated potassium channels play a key role in facilitating synthesis and/or release of endothelium‐derived NO in the rat basilar artery (CIHR).