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Intercellular electrical communication among smooth muscle and endothelial cells in guinea‐pig mesenteric arterioles
Author(s) -
Yamamoto Yoshimichi,
Klemm Megan F.,
Edwards Frank R.,
Suzuki Hikaru
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00181.x
Subject(s) - gap junction , biophysics , intracellular , anatomy , acetylcholine , biology , endothelium , myocyte , endothelial stem cell , cell junction , connexin , vascular smooth muscle , membrane potential , electrophysiology , microbiology and biotechnology , smooth muscle , cell , endocrinology , neuroscience , biochemistry , in vitro
1 Current clamp studies using two patch electrodes and morphological observations have been performed in guinea‐pig mesenteric arterioles to evaluate intercellular electrical couplings. 2 In electron micrographs, preparations were found to have a single layer of smooth muscle cells. Typical gap junctions were readily observed between endothelial cells only. 3 While immunoreactivity to connexin 40 was strongly expressed on the membranes of endothelial cells only, that to connexin 43 was expressed on both smooth muscle and endothelial cell membranes. 4 Neurobiotin injected into a smooth muscle cell diffused into several neighbouring smooth muscle cells while that injected into an endothelial cell diffused into many endothelial cells. 5 Acetylcholine‐induced hyperpolarizations were conducted from endothelial cells to smooth muscle cells with a relative amplitude of 80.1 %. Ba 2+ ‐induced action potentials were conducted in the opposite direction with a relative amplitude of 92.4 %. 6 An electrotonic potential produced in a smooth muscle cell by current injection diminished steeply with distance as it spread along the muscle layer, plateauing at distances beyond 25 μm. An electrotonic potential produced in an endothelial cell spread within the intima with virtually no reduction. Electrotonic potentials could conduct through myoendothelial couplings, which seemed to behave as ohmic resistors without rectification. 7 The coupling resistance between adjacent smooth muscle cells was estimated to be at least 90 MΩ and that between a smooth muscle cell and the whole endothelial layer to be 0.9 GΩ. 8 The results indicate that although the resistance of myoendothelial couplings is appreciable, the endothelium may be important as a low resistance path connecting many smooth muscle cells.