Endothelial Gi protein expression is markedly low in human coronary microvessels

Hiroaki Shimokawa, Masato Tsutsui, Tsunetaka Mizuki, Kazunori Hase, Isao Kuwaoka, Naoe Nogami, Shuichi Okamatsu, Kazuo Nakanishi

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Gi protein functionally mediates endothelium-dependent relaxations in large epicardial coronary arteries but not in small coronary arteries, which suggests a different involvement of Gi protein in the endothelium-dependent relaxations between large and small coronary arteries. We previously showed that endothelial Gi protein is present in human epicardial coronary artery. In the present study, we examined the expression of endothelial Gi protein in human coronary microvessels. Immunohistochemical staining with a specific antibody against human Gi protein was performed in intramyocardial coronary microvessels and vasa vasorum from 34 autopsy cases. The immunoreactive levels of the endothelial Gi protein were semiquantitated into four grades (none, 0; slight, +1; moderate, +2; high, +3), and the mean value of the ratings of all endothelial cells was then used as an index of the endothelial Gi protein expression of the vessel. The immunoreactive levels of the endothelial Gi protein were extremely low in intramyocardial coronary microvessels and in vasa vasorum, irrespective of the age of the patients, the presence or absence of coronary risk factors, or the influence of medical treatments. These results may therefore explain in part why endothelium-dependent relaxations in coronary microvessels are not functionally mediated by Gi protein.

Original languageEnglish
Pages (from-to)297-302
Number of pages6
JournalJournal of cardiovascular pharmacology
Volume27
Issue number2
DOIs
Publication statusPublished - 1996

Keywords

  • Coronary microvessels
  • Endothelium-dependent relaxation
  • Endothelium-derived relaxing factor
  • Gi proteins
  • Nitric oxide
  • Pertussis toxin

ASJC Scopus subject areas

  • Pharmacology
  • Cardiology and Cardiovascular Medicine

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