Generation of Free Radicals and the Damage Done to the Sarcoplasmic Reticulum During Reperfusion Injury Following Brief Ischemia in the Canine Heart

Abstract

Free radical generation was studied by the electron spin resonance (ESR) technique using -phenyl N tert butyl nitrone (PBN) in a brief ischemia-reperfusion model of the canine heart, and correlated with biochemical changes of the sarcoplasmic reticulum (SR). ESR spectra (aH = 0.3-0.4 mT, aN = 1.43-1.58 mT) were observed as PBN spin adducts, which peaked at levels 5-fold above the control levels at 5 min after reperfusion. The simulated coupling constants of PBN spin adducts suggested that the sample should contain at least 2 carbon-centered radicals at 5 min after reperfusion (radical A: aH = 0.350 mT, aN = 1.485 mT; radical B: aH = 0.370 mT, aN = 1.615 mT). At this time point, a significant reduction in Ca-ATPase activity of the SR was found without degradation of the major ATPase protein. Superoxide dismutase (SOD) significantly reduced the intensity of the PBN spin adduct signals and preserved the Ca-ATPase activity of the SR to 80% of the control level. Reperfusion injury after brief ischemia may be the result of inactivation of intracellular Ca-ATPase by free radicals generated during reperfusion, and SOD contributes to the protective effect by scavenging the radicals. (Jpn Circ J 1999; 63: 373 -378)

Detection of free radicals in ischemic and reperfused canine gracilis muscle flaps by use of spin-trapping electron paramagnetic resonance spectroscopy

“…32 Oxygen-and carbon-centered radical adducts of PBN have been detected in other canine ischemia-reperfusion systems. 3,7,28,[33][34][35] We did not detect a signal indicating the presence of free radicals in control muscle flaps. This result supports the hypothesis that free radicals are not produced in high concentrations in perfused canine gracilis muscle, even after flap dissection and transection of minor vascular pedicles and nerves.…”

“…This free radical adduct is thought to originate as a degradation product of the hydroxyl radical adduct of PBN. 7,26 Large deflections consistent with the presence of manganese ions 27,28 were detected in spectra obtained from effluent blood of ischemic and reperfused flaps from 2 dogs and in spectra from blood from a control flap (Fig 3).…”

Expression of the Nrf2‐system at the blood‐CSF barrier is modulated by neonatal inflammation and hypoxia‐ischemia

“…Nrf2 is a key regulator of endogenous antioxidant systems (Itoh et al 1999; Johnson et al 2002; Lee et al 2003) and has been shown to play a neuroprotective role in the adult by preserving blood–brain barrier function following traumatic brain injury (Zhao et al 2007). Activation of Nrf2 by isothiocyanates in vitro was recently reported to protect from oxidative damage at the blood-CSF interface by maintaining low permeability of choroid plexus epithelial cells subjected to H 2 O 2 stress (Xiang et al 2012).…”

Inhibition by KB-R7943 of the Reverse Mode of the Na+/Ca2+ Exchanger Reduces Ca2+ Overload in Ischemic-Reperfused Rat Hearts.

“…actors that affect the process of myocardial injury induced by ischemia -reperfusion include free radicals, 1 oxygen tension 2 and the ATP-sensitive K + channel. 3 Intracellular Ca 2+ overload also leads to myocardial injury in ischemia -reperfusion [4][5][6][7][8] and the sarcolemmal Na + /Ca 2+ exchanger (NCX) is thought to be a major factor in the excessive Ca 2+ influx.…”