Although GJ-mediated intercellular communication between cells of the vascular wall has, in general, been recognized to play a key role in the coordination of vascular function, the role of GJ in capillary endothelial cells has not yet been completely clarified. Available indirect in vivo evidence implicates capillary GJ participation in capillary-arte-riolar communication and the feedback pathway of local blood flow control. Microvascular endothelial cells grown in vitro retain their ability to respond to vasoactive stimuli and to communicate these responses via gap junctions. Thus, concerted research efforts should be undertaken to provide the necessary direct in vivo evidence to firmly establish participation of capillary GJs in local blood flow control under normal and pathophysiological conditions.
Capillary: The smallest blood vessel (~5 mm in diameter in mammalian tissues) lacking continuous muscular layer.
Electrotonic spread: Passive spread of electrical current (e.g., carried by the ions of the cell cytosol) whose amplitude decays with distance.
Gap junction: Intercellular channel directly connecting the cytosols of two adjacent cells.
Sepsis: Systemic inflammatory response to local infection.
This research was supported by the Canadian Institutes of Health Research and Heart and Stroke Foundation of Ontario.
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K. Tyml is a professor at the Department of Medical Biophysics, University of Western Ontario. His research interests include local micro-vascular blood flow control, arteriolar reactivity, and the role of capillaries and vascular cell-to-cell communication in this control. Recently, he has examined the pathophysiological effects of skeletal muscle disuse, and sepsis, and the protective effect of vitamin C, on this local control.
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