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Electrotonic transmission within pericyte-containing retinal microvessels
David M Wu1, Masahiro Minami, Hajime Kawamura
1Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan 48105, USA.
Microcirculation (New York, N.Y. : 1994)
|July 4, 2006
Summary
Retinal microvessels show efficient electrical communication within endothelial cells, coordinating pericyte responses. This suggests the endothelium plays a key role in regulating blood flow in the retina.
Area of Science:
- Neuroscience
- Ophthalmology
- Physiology
Background:
- The electrotonic architecture of the pericyte-rich retinal microvasculature is not well understood.
- Cell-to-cell transmission of hyperpolarization is a key factor that can influence pericyte relaxation and lumen dilation.
Purpose of the Study:
- To investigate the electrotonic properties of the retinal microvasculature.
- To understand the role of cell-to-cell communication in regulating retinal blood flow.
Main Methods:
- Utilized perforated-patch pipettes to monitor membrane potentials and ionic currents in rat retinal pericytes.
- Induced voltage changes via electrical stimuli, KATP channel opener pinacidil, and oxotremorine.
- Assessed cell-to-cell transmission and the effect of the gap junction uncoupler heptanol.
Main Results:
- Demonstrated extensive cell-to-cell communication with similar spontaneous voltage changes in distant pericytes.
- Confirmed functional electrical coupling between pericytes, which was blocked by heptanol.
- Observed efficient spread of hyperpolarization within 100 micrometers, with minimal decay for pinacidil-induced changes.
Conclusions:
- Retinal microvessels exhibit efficient cell-to-cell communication within the endothelium.
- Transmission at pericyte/endothelial junctions is relatively inefficient.
- The endothelium likely serves as an efficient pathway linking contractile pericytes to coordinate vasomotor responses in retinal capillaries.