Calcium imaging of murine thoracic aorta endothelium by confocal microscopy reveals inhomogeneous distribution of endothelial cells responding to vasodilator agents

J Vasc Res. 2002 May-Jun;39(3):260-7. doi: 10.1159/000063691.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine / metabolism
  • Acetylcholine / pharmacology
  • Adenosine Triphosphate / metabolism
  • Adenosine Triphosphate / pharmacology
  • Animals
  • Aorta, Thoracic / drug effects*
  • Aorta, Thoracic / metabolism
  • Aorta, Thoracic / ultrastructure
  • Bradykinin / metabolism
  • Bradykinin / pharmacology
  • Calcium / metabolism*
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / metabolism
  • Endothelium, Vascular / ultrastructure
  • Isometric Contraction / drug effects
  • Mice
  • Microscopy, Confocal / methods
  • Substance P / metabolism
  • Substance P / pharmacology
  • Vasodilator Agents / metabolism
  • Vasodilator Agents / pharmacology*

Substances

  • Vasodilator Agents
  • Substance P
  • Adenosine Triphosphate
  • Acetylcholine
  • Bradykinin
  • Calcium