title: Calcium imaging of murine thoracic aorta endothelium by confocal microscopy reveals inhomogeneous distribution of endothelial cells responding to vasodilator agents.
abstract: The aim of the study was to assess, in intact murine thoracic aorta in vitro, the distribution of endothelial cells responsive to endothelium-dependent vasodilators ACh, ATP, bradykinin and substance P, using laser line confocal microscopy in combination with two Ca2+ fluorescent dyes, Fluo-4 and Fura-red. We observed that 82 +/- 3% of endothelial cells responded to ATP, 33 +/- 5% to Ach, whereas less than 3% of them responded to bradykinin or substance P. In order to determine whether the findings of pharmacological tests agree with confocal microscopy data, endothelium-dependent vasodilators induced relaxation was evaluated using isometric tension measurement. We show a marked correlation between a higher number of activated endothelial cells, using confocal microscopy, and a greater degree of endothelium-dependent relaxation using isometric tension measurement (p = 0.00286). Our results suggest that endothelial cells responding to endothelium-dependent vasodilators are not homogeneously distributed in intact murine thoracic aorta. This could be due to nonhomogeneous distribution of surface receptors or to differences in post-receptor coupling mechanisms.
authors.affiliation: Department of Internal Medicine, Centre Hospitalier Universitaire de Rouen-Boisguillaume, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Marie
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Bény
mesh_terms: D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D001920:Bradykinin / Q000378:metabolism / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D007537:Isometric Contraction / Q000187:drug effects; D051379:Mice; D018613:Microscopy, Confocal / Q000379:methods; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology; D014665:Vasodilator Agents / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D013373:Substance P; D000255:Adenosine Triphosphate; D000109:Acetylcholine; D001920:Bradykinin; D002118:Calcium