Use of spin traps in intact animals undergoing myocardial ischemia/reperfusion: A new approach to assessing the role of oxygen radicals in myocardial "stunning"

Roberto Bolli, Paul B. Mccay

Research output: Contribution to journalArticlepeer-review

Abstract

Numerous studies have indirectly, suggested that oxygen-derived free radicals play an important path-ogenetic role in the prolonged depression of contractile function observed in myocardium reperfused after reversible ischemia (myocardial "stunning" In order to provide direct evidence for the oxy-radical hypothesis of stunning, we administered the spin trap, αphenyl N-tert-butyl nitrone (PBN), to open-chest dogs undergoing a 15-min coronary artery occlusion followed by reperfusion. Plasma of local coronary venous blood was analyzed by electron paramagnetic resonance (EPR) spectroscopy. EPR signals characteristic of radical adducts of PBN appeared during ischemia and increased dramatically in the first few minutes after reperfusion. After this initial burst, the production of adducts abated but did not cease, persisting up to 3 h after reflow. The production of PBN adducts after reperfusion was inversely related to collateral flow during ischemia. PBN itself enhanced recovery of contractile function. indicating that the radicals trapped may play a pathogenetic role in myocardial stunning. Superoxide dismutase plus catalase attenuated PBN adduct production and, at the same time, improved recovery of contractile function. Antioxidant therapy given 1 min before reperfusion suppressed PBN adduct production and improved contractile recovery; however, the same therapy given 1 min after reperfusion did not suppress early radical production and did not attenuate contractile dysfunction. After i.v. administration, the elimination half-life of PBN was estimated to be approximately 4-5 h. The results demonstrate that 1) free radicals are produced in the stunned myocardium in intact animals; 2) inhibition of free radical production results in improved contractile recovery; and 3) the free radicals important in causing dysfunction are produced in the first few minutes of reperfusion. Taken together, these studies provide cogent evidence supporting the oxy-radical hypothesis of stunning in open-chest dogs. It is now critical to determine whether these results can be reproduced in conscious animal preparations.

Original languageEnglish (US)
Pages (from-to)169-180
Number of pages12
JournalFree Radical Research
Volume9
Issue number3-6
DOIs
StatePublished - 1990
Externally publishedYes

Keywords

  • Coronary artery reperfusion
  • Electron paramagnetic resonance spectroscopy
  • Free oxygen radicals
  • Myocardial dysfunction
  • Spin traps
  • αphenyl N-tert-butyl nitrone

ASJC Scopus subject areas

  • Biochemistry

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