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Electrotonic Transmission Within Pericyte‐Containing Retinal Microvessels
Author(s) -
WU DAVID M.,
MINAMI MASAHIRO,
KAWAMURA HAJIME,
PURO DONALD G.
Publication year - 2006
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680600745778
Subject(s) - pericyte , gap junction , pinacidil , hyperpolarization (physics) , retinal , biophysics , heptanol , neurotransmission , retina , membrane potential , chemistry , neuroscience , intracellular , anatomy , biology , microbiology and biotechnology , endothelial stem cell , biochemistry , endocrinology , glibenclamide , receptor , organic chemistry , nuclear magnetic resonance spectroscopy , in vitro , diabetes mellitus
Objective: Little is known about the electrotonic architecture of the pericyte‐containing retinal microvasculature. Here, the authors focus on the cell‐to‐cell transmission of hyperpolarization, which can induce abluminal pericytes to relax and lumens to dilate. Methods: With perforated‐patch pipettes, the authors monitored the membrane potentials and ionic currents of pairs of pericytes located on freshly isolated rat retinal microvessels. Voltage changes were induced by administering electrical stimuli into pericytes, miniperfusing the K ATP channel opener pinacidil, or using oxotremorine to activate chloride channels. Results: Suggestive of extensive cell‐to‐cell communication, spontaneous voltage changes were strikingly similar in widely separated pericytes. In addition, injection of current into one of a pair of sampled pericytes always elicited a voltage response in the other sampled pericyte; the gap junction uncoupler, heptanol, blocked this transmission. In the dual recordings, hyperpolarization spreading from a current‐injected pericyte decayed ∼40% within 100 μ m. In contrast, pinacidil‐induced hyperpolarizations diminished by only ∼ 2% in 100 μ m. Depolarizations also appeared to spread with similar transmission efficacies. Conclusions: Based on the experiments, the authors propose that key features of the electrotonic architecture of retinal microvessels include highly efficient cell‐to‐cell communication within the endothelium and relatively inefficient transmission at pericyte/endothelial junctions. Thus, the endothelium is likely to provide an efficient pathway that functionally links contractile pericytes and thereby, serves to coordinate the vasomotor response of a retinal capillary.