title: Endothelial feedback and the myoendothelial projection.
abstract: The endothelium plays a critical role in controlling resistance artery diameter, and thus blood flow and blood pressure. Circulating chemical mediators and physical forces act directly on the endothelium to release diffusible relaxing factors, such as NO, and elicit hyperpolarization of the endothelial cell membrane potential, which spreads to the underlying smooth muscle cells via gap junctions (EDH). It has long been known that arterial vasoconstriction in response to agonists is limited by the endothelium, but the question of how contraction of smooth muscle cells leads to activation of the endothelium (myoendothelial feedback) has, until recently, received little attention. Initial studies proposed the permissive movement of Ca(2+) ions from smooth muscle to endothelial cells to elicit release of NO. However, more recent evidence supports the notion that flux of IP(3) leading to localized Ca(2+) events within spatially restricted myoendothelial projections and activation of EDH may underlie myoendothelial feedback. In this perspective, we review recent data which supports the functional role of myoendothelial projections in smooth muscle to endothelial communication. We also discuss the functional evidence supporting the notion that EDH, as opposed to NO, is the primary mediator of myoendothelial feedback in resistance arteries.
authors.affiliation: Faculty of Health and Community Studies, MacEwan University, Robbins Health Learning Centre, Edmonton, Alberta, Canada.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Kerr
authors.forename: Raymond
authors.initials: R
authors.lastname: Tam
authors.forename: Katarina
authors.initials: K
authors.lastname: Ondrusova
authors.forename: Rohan
authors.initials: R
authors.lastname: Mittal
authors.forename: Deepak
authors.initials: D
authors.lastname: Narang
authors.forename: Cam Ha T
authors.initials: CH
authors.lastname: Tran
authors.forename: Donald G
authors.initials: DG
authors.lastname: Welsh
authors.forename: Frances
authors.initials: F
authors.lastname: Plane
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D017629:Gap Junctions / Q000378:metabolism*; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D014655:Vascular Resistance / Q000502:physiology*
chemical_list: D009569:Nitric Oxide; D002118:Calcium