Endothelium-dependent smooth muscle hyperpolarization: do gap junctions provide a unifying hypothesis?
An endothelium-derived hyperpolarizing factor (EDHF) that is distinct from nitric oxide (NO) and prostanoids has been widely hypothesized to hyperpolarize and relax vascular smooth muscle following stimulation of the endothelium by agonists. Candidates as diverse as K(+) ions, eicosanoids, hydrogen peroxide and C-type natriuretic peptide have been implicated as the putative mediator, but none has emerged as a 'universal EDHF'. An alternative explanation for the EDHF phenomenon is that direct intercellular communication via gap junctions allows passive spread of agonist-induced endothelial hyperpolarization through the vessel wall. In some arteries, eicosanoids and K(+) ions may themselves initiate a conducted endothelial hyperpolarization, thus suggesting that electrotonic signalling may represent a general mechanism through which the endothelium participates in the regulation of vascular tone.
Griffith
Tudor M
TM
Department of Diagnostic Radiology, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN. griffith@cardiff.ac.uk
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002450:Cell Communication; D017630:Connexins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000502:physiology*; D017629:Gap Junctions / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D020098:Natriuretic Peptide, C-Type / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D024681:Potassium Channels, Calcium-Activated / Q000502:physiology; D014664:Vasodilation / Q000502:physiology
D017630:Connexins; D024681:Potassium Channels, Calcium-Activated; D020098:Natriuretic Peptide, C-Type; D016718:Arachidonic Acid; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010741:Phospholipases A; D011188:Potassium