Articles |
From the Laboratory of Molecular Biophysics (W.C., S.G., E.M.), National Institute of Environmental Health Sciences, Research Triangle Park, NC, and the Department of Pathology (C.S.), Duke University Medical Center, Durham, NC.
Correspondence to Dr W. Chen, MD 4A-01, PO Box 12233, NIEHS, Research Triangle Park, NC 27709.
| Abstract |
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Key Words: preconditioning thiol redox glutathione ischemia/reperfusion
| Introduction |
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B, and the
activity of several kinases and phosphatases are subject to redox
regulation.1 2 3 4 5 6 TNF-
reduces cellular levels of
glutathione and inactivates a redox-sensitive protein
phosphatase.7 Similarly, protein tyrosine kinase, an
endoplasmic reticulumassociated tyrosine kinase, has been shown to be
affected by redox regulation; diamide, a thiol-oxidizing agent,
activates this kinase.8 A redox-based mechanism has also
been invoked to account for the differential effect of nitric oxide on
neuroprotection and neurodestruction.9 Also, many ion
transporters and channels, such as the
Na+-Ca2+ exchanger and Na+
and Ca2+ channels, have been shown to be sensitive
to cellular redox state.10 11 In view of the wealth of data suggesting that mild redox alterations can affect cell function, we tested the hypothesis that a redox change might be responsible for the cardioprotective effect conferred by ischemic preconditioning, the phenomenon whereby one or more brief intermittent periods of ischemia, each separated by brief periods of reflow, can reduce the area of necrosis, reduce the severity of arrhythmias, and improve functional recovery after a subsequent longer period of ischemia.12 13 14 15 16 17 We report in the present study that preconditioning with four 5-minute periods of ischemia, each separated by 5 minutes of reflow, is associated with loss of glutathione in Langendorff-perfused rat hearts and that this loss is prevented by the addition of NAC, a glutathione precursor and antioxidant, during the preconditioning protocol. We further report that the addition of NAC during preconditioning blocks or diminishes the protective effects of preconditioning: the decrease in acidification during ischemia, the improvement in functional recovery on reflow after 20 minutes of ischemia, and the decrease in creatine kinase release on reflow after 60 minutes of ischemia. Thus, a redox-sensitive mechanism may be involved in the protection afforded by ischemic preconditioning.
| Materials and Methods |
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25 mg). The animals were heparinized (200 U IV), the
heart was rapidly excised, and the aorta was cannulated. Retrograde
perfusion was begun under constant pressure (90 cm H2O).
The nonrecirculating perfusate was a Krebs-Henseleit buffer containing
(mmol/L) NaCl 120, KCl 4.7, MgSO4 1.2,
KH2PO4 1.2, CaCl2 1.25,
NaHCO3 25, and glucose 11. The buffer was maintained at pH
7.4 by bubbling with a mixture of 95% O2/5%
CO2 and at a temperature of 37°C.
To monitor contractility, a latex balloon connected to
a Statham pressure transducer was inserted into the left ventricle. The
balloon was inflated to give an end-diastolic pressure of 5
to 10 cm H2O. Global ischemia was created by
cross-clamping the perfusate inflow line. To decrease the
"no-reflow" region at the end of the ischemic period, the
balloon was collapsed, and the heart was reperfused. After a few
minutes of reperfusion, the balloon was reinflated to an
end-diastolic pressure of
5 to 10 cm H2O to
assess recovery of contractile function.
31P Nuclear Magnetic Resonance
Rat hearts were bathed in the perfusate for optimal magnetic
susceptibility matching. Hearts were placed in a 20-mm NMR tube, and
the perfusate was switched to phosphate-free Krebs-Henseleit buffer so
that the inorganic phosphate resonance detected by 31P NMR
would be composed of only intracellular phosphate. 31P NMR
spectra were obtained at 146.1 MHz by using a Nicolet wide-bore NT-360
spectrometer. The temperature of the heart was maintained at
37±0.5°C by the variable temperature unit of the Nicolet NT-360.
We shimmed on the proton signal from the heart and routinely obtained a
nonspinning line width at one-half height of
0.2 ppm. Spectra were
acquired every 5 minutes by using a 2-second interval between scans
with a pulse of 70° (35 microseconds). The spectral width was ±3425
Hz, and 4000 data points were collected. The free-induction decay was
multiplied by an exponential function corresponding to 40-Hz line
broadening before Fourier transformation. The pHi
determination was made from the chemical shift difference between the
intracellular inorganic phosphate and phosphocreatine
peaks.18
Biochemical Assays
Glutathione was measured from 100 to 200 mg of heart tissue that
was homogenized with 3 mL of 6% (vol/vol) perchloric acid
in liquid nitrogen, and the supernatant, obtained after
centrifugation at 9000g for 10 minutes, was
neutralized with 2 mol/L K2CO3. Total
glutathione (GSH+GSSG) in the sample was determined by measuring the
rate of 5,5'-dithiobis-2-nitro-5-thiobenzoic acid reduction by GSH,
detected at 412 nm.19 The reaction mixture included 0.6
mmol/L 5,5'-dithiobis-2-nitro-5-thiobenzoic acid, 0.21 mmol/L NADPH,
and 0.5 U glutathione reductase in 125 mmol/L phosphate buffer (pH 7.5)
in a total volume of 1 mL, and the assay was performed at 25°C. The
concentration in the sample was evaluated by comparison with the
standard curve. The tissue glutathione content is expressed as
micromoles per gram dry weight.
Creatine kinase activity was measured spectrophotometrically at 25°C20 by using a creatine kinase kit containing a sulfhydryl-reducing agent, NAC, in the assay mixture.
Experimental Procedures
As illustrated in Fig 1
, three sets of
experiments were performed: to evaluate function and
metabolism (protocol A), to measure creatine kinase release
(protocol B), and to assay glutathione content (protocol C).
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Protocol A: Function, Energy Metabolism, and
pHi
These studies were performed in the NMR spectrometer, and as
shown in Fig 1A
, pHi and high-energy phosphates were
measured throughout the experimental procedure. LVDP was also monitored
continuously; we report recovery of LVDP measured at 20 minutes of
reflow. The protocol consisted of a 25-minute control/equilibration
period, a 40-minute treatment period, a 20-minute global
normothermic ischemia period, and a 20-minute
reperfusion period. The differences in treatment period are summarized
as follows: In group I (control, n=5), hearts were perfused with
phosphate-free Krebs-Henseleit buffer. In group II (NAC, n=7), 4 mmol/L
NAC (Sigma Chemical Co) was added to the perfusate during the 40-minute
treatment period. In group III (PC, n=7), hearts were preconditioned
with four cycles of 5 minutes of ischemia each separated by 5
minutes of reflow. Group IV (PC+NAC, n=7) was identical to group III
except that 4 mmol/L NAC was added to the perfusate 10 minutes before
preconditioning and was present throughout the preconditioning
protocol. During the final 20-minute reperfusion period, all hearts
were perfused with Krebs-Henseleit buffer without NAC.
Protocol B: Creatine Kinase Release
The same protocol as described above was followed except that to
allow measurable creatine kinase release, the duration of global
ischemia was extended to 60 minutes (Fig 1B
). The
coronary effluent was collected during 20 minutes of
reperfusion, and creatine kinase activity was measured. The same four
groups of hearts were studied: group I (control, n=5), group II (NAC,
n=5), group III (PC, n=6), and group IV (PC+NAC, n=5). Creatine kinase
release during 20 minutes of reperfusion is expressed as IU per 20
minutes per gram dry weight (IU · 20 min-1 · g dry
wt-1).
These studies were also performed in the NMR spectrometer to allow 31P NMR monitoring. Measurements of pHi and ATP during the preischemic period and 20 minutes of ischemia include data from protocols A and B, whether the total duration of ischemia was 20 minutes or 60 minutes, but the reflow data do not include the hearts subjected to 60 minutes of ischemia. Therefore, for the pHi and ATP measurements, the number of hearts per group was greater than that for the recovery of LVDP (only from protocol A). ATP and pHi experiments are as follows: group I (control, n=10), group II (NAC, n=12), group III (PC, n=13), and group IV (PC+NAC, n=12).
Protocol C: Glutathione Content
The same protocol as above was followed except that at the end
of the treatment period (ie, immediately before sustained
ischemia), the heart was freeze-clamped by tongs precooled with
liquid nitrogen (Fig 1C
). Four groups of hearts were studied: group I
(control, n=14), group II (NAC, n=6), group III (PC, n=8), and group IV
(PC+NAC, n=9).
Statistics
Values are expressed as mean±SEM. Statistical analysis
(for glutathione content, creatine kinase release, and LVDP recovery)
was performed by a SYSTAT 5 program using fully factorial
(M)ANOVA. The time-dependent ATP and pHi data were
subjected to ANOVA for repeated measurements. When ANOVA demonstrated
that significant differences existed, a post hoc (Tukey) test was
performed. The level of statistical significance was
P<.05.
| Results |
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Role of Thiol Redox State in Preconditioning
It has been well documented that compared with
nonpreconditioned perfused rat hearts, hearts
preconditioned with four cycles of 5 minutes of ischemia and 5
minutes of reperfusion show improved recovery of LVDP (measured on
reflow after 20 to 30 minutes of sustained ischemia) and
reduced release of the intracellular enzyme creatine kinase during
reflow after 60 minutes of sustained
ischemia.14 15 16 17 To determine if a redox change
occurs during the preconditioning protocol, we measured glutathione
levels, which provide an index of thiol oxidation. As shown in Fig 2
, preconditioning leads to a reduction in glutathione
levels to 3.98±0.32 µmol/g dry wt compared with no preconditioning
(6.38±0.24 µmol/g dry wt). Furthermore, addition of NAC during
preconditioning blocks this decline in glutathione (5.60±0.31 µmol/g
dry wt). NAC alone did not significantly alter glutathione levels.
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We reasoned that if a redox mechanism were responsible for the
protection induced by preconditioning, then inhibition of the redox
change during preconditioning should block these beneficial effects. As
shown in Figs 3
and 4
, NAC treatment by
itself has no effect on recovery of LVDP or creatine kinase release
after ischemia in nonpreconditioned hearts
(group II). The addition of NAC during the preconditioning period,
however, blocks the preconditioning-induced improvement in
postischemic contractile function and decrease in enzyme
release. As shown in Fig 3
, recovery of LVDP after 20 minutes of
ischemia was 91±11% in PC hearts compared with 24±6%
(P<.05) in PC+NAC hearts. Recovery of LVDP in hearts
treated with NAC alone (22±7%) was not significantly different than
that observed in control hearts (38±7%, P>.05).
Furthermore, the recovery of LVDP in control hearts (group I), NAC
hearts (group II), and PC+NAC hearts (group IV) did not differ
significantly. Similarly, as shown in Fig 4
, creatine kinase release
during 20 minutes of reflow after 60 minutes of ischemia was
significantly less in PC hearts (170±26 IU · 20
min-1 · g dry wt-1) than in PC+NAC hearts
(361±30 IU · 20 min-1 · g dry wt-1),
control hearts (271±20 IU · 20 min-1 · g dry
wt-1), or NAC hearts (261±34 IU · 20
min-1 · g dry wt-1). Thus, hearts
preconditioned in the presence of NAC had levels of creatine kinase
release and recovery of LVDP that were not significantly different from
those found in nonpreconditioned hearts but were
significantly different from those in hearts preconditioned without
NAC.
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Ischemia has been shown to cause a large decline in
pHi, and preconditioning has been shown by several
groups to attenuate the decline in pHi during the sustained
period of ischemia.16 17 This reduced
acidification could be beneficial in reducing calcium overload during
ischemia and reflow.16 If a change in thiol redox
state is the mediator of preconditioning and reduced ionic derangements
are involved in preconditioning, then it might be expected that
blocking thiol redox changes by perfusion with NAC would block the
ability of preconditioning to reduce acidification. Interestingly, as
shown in Fig 5
, the effect of preconditioning on the
decline in pHi during ischemia is attenuated by the
addition of NAC. We find that NAC treatment by itself in
nonpreconditioned hearts did not alter the time course
or extent of decline in pHi during ischemia. In NAC
hearts (group II), pHi decreased to 6.03±0.08 during 15 to
20 minutes of ischemia, similar to that in untreated (control)
hearts (5.96±0.12, P>.05). However, PC+NAC hearts showed
pHi values (6.29±0.03) during 15 to 20 minutes of
sustained ischemia that were intermediate between the NAC
hearts (6.03±0.08) and the PC hearts (6.43±0.03); pHi
values (at 15 to 20 minutes) in these three groups were significantly
different from each other (P<.05).
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The time course of changes in ATP during the preischemic
period, 20 minutes of ischemia, and 20 minutes of reflow in all
groups is depicted in Fig 6
. There were no significant
differences in the decline in ATP content during ischemia. Upon
reperfusion, ATP recovered to
30% in all groups. In addition,
recovery of phosphocreatine content (
90% of the initial value) and
coronary flow (
80% of the initial value) was not
significantly different among the groups, indicating that the
differences in recovery of LVDP were not due to differences in
perfusion.
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| Discussion |
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-glutamylcysteine synthase and glutathione
synthase.24 25 The first step is controlled by feedback
inhibition by glutathione. This negative-feedback mechanism seems
normally to determine the upper level of intracellular glutathione,
even in the presence of NAC. In the present study, postischemic functional recovery and creatine kinase release in NAC-treated nonpreconditioned hearts did not differ significantly from those in untreated hearts, indicating that NAC treatment by itself is not detrimental. In fact, in the previous studies, NAC treatment was found to improve postischemic functional recovery and to decrease creatine kinase release in the perfused rabbit heart subjected to 60 minutes of low-flow ischemia (1 mL/min),23 when 1 µmol/L NAC was given throughout the experimental protocol (including before, during, and after ischemia). In other studies, NAC, also administered throughout the experiment, has been shown to reduce myocardial stunning, but NAC administration failed to limit infarct size in an in vivo canine model26 and failed to reduce creatine kinase release in an in vitro rat model.27 These authors attributed the protective effects of NAC to the increased thiol availability and/or direct scavenging of oxygen-derived free radicals, which presumably were produced during the early reperfusion period, by NAC. In the present study, when NAC was perfused only before the sustained period of ischemia, we found that NAC was not protective.
NAC in Preconditioned Hearts
Numerous studies have documented that small changes in thiol redox
potential can exert signaling functions that can be blocked by high
levels of thiol antioxidants. Previous studies have shown that
transient thiol oxidation results in a modest reduction in glutathione
levels, which is critical for the activation of NF-
B by TNF-
,
since NAC blocks both the decrease in glutathione and the activation of
NF-
B.3 The present study and other
studies1 2 3 4 5 6 7 8 show that thiol redox potential can exert a
regulatory role in cellular metabolism in a manner
comparable to phosphorylation and
dephosphorylation.
The present study shows that during preconditioning, there is thiol oxidation during the brief cycles of ischemia and reperfusion, resulting in loss of glutathione. This is prevented by NAC, either because NAC serves as an antioxidant that minimizes glutathione oxidation or because NAC serves as a substrate to replenish glutathione when tissue glutathione is decreased and the synthase becomes active. The data in the present study illustrate that a redox-sensitive mechanism can play a role in the protective effects of ischemic preconditioning in the heart. Although prevention of thiol oxidation is associated with protection against oxidative injury induced by toxic drugs and other stresses, during preconditioning, thiol oxidation is associated with adaptive responses that protect cardiac myocytes from subsequent ischemic injury.
The data in the present study are also consistent with the hypothesis that free radicals are mediators of preconditioning28 29 and that NAC either directly or via glutathione negates this mediator. Previous work on the effect of antioxidants in ischemic preconditioning has produced conflicting results. Richard et al30 found that perfusion with MPG before and during preconditioning in the in vivo rat did not affect the ability of preconditioning to reduce infarct size. Conversely, Tanaka et al29 found that perfusion with MPG or superoxide dismutase diminished the protective effect of preconditioning on infarct size in the in vivo rabbit heart. However, neither of these studies measured glutathione; therefore, the effectiveness of the antioxidants is difficult to assess. In the present study, perfusion with NAC prevented the loss of glutathione and reversed the protective effect of preconditioning on postischemic recovery of contractile function and on enzyme release.
Previous investigators have tested the hypothesis that the protective effect of preconditioning might be mediated by an increase in antioxidant defenses, but experimental data suggest that antioxidant defenses are not increased in preconditioned rabbit myocardium.31 Contrary to the expectation that preconditioning might be associated with increased protection against oxidation, the present study suggests that thiol oxidation during the preconditioning protocol may actually be protective and that elimination of thiol oxidation during the preconditioning protocol, by treatment with NAC, blocks the protective effects of preconditioning in rat heart.
Thus, we have shown that preconditioning is associated with a more oxidized cellular redox state, as measured by the loss of glutathione. If we block this more oxidized redox state by the addition of NAC during preconditioning, we block the protective effects of preconditioning. Hearts preconditioned in the presence of NAC have a greater decline in pHi during ischemia than hearts preconditioned in the absence of NAC, and hearts preconditioned in the presence of NAC show no improvement in recovery of function and no diminution in enzyme release compared with nonpreconditioned hearts. These data support the hypothesis that redox control is important in the protection afforded by preconditioning.
| Selected Abbreviations and Acronyms |
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| Acknowledgments |
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Received March 9, 1995; accepted April 19, 1995.
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I. Koramaz, Z. Pulathan, S. Usta, S. C. Karahan, A. Alver, E. Yaris, N. I. Kalyoncu, and F. Ozcan Cardioprotective Effect of Cold-Blood Cardioplegia Enriched with N-Acetylcysteine During Coronary Artery Bypass Grafting Ann. Thorac. Surg., February 1, 2006; 81(2): 613 - 618. [Abstract] [Full Text] [PDF] |
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B. O'Rourke, S. Cortassa, and M. A. Aon Mitochondrial Ion Channels: Gatekeepers of Life and Death Physiology, October 1, 2005; 20(5): 303 - 315. [Abstract] [Full Text] [PDF] |
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S. A. R. Paiva, R. Novo, B. B. Matsubara, L. S. Matsubara, P. S. Azevedo, M. F. Minicucci, A. O. Campana, and L. A. M. Zornoff {beta}-Carotene Attenuates the Paradoxical Effect of Tobacco Smoke on the Mortality of Rats after Experimental Myocardial Infarction J. Nutr., September 1, 2005; 135(9): 2109 - 2113. [Abstract] [Full Text] [PDF] |
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T. Tojo, M. Ushio-Fukai, M. Yamaoka-Tojo, S. Ikeda, N. Patrushev, and R. W. Alexander Role of gp91phox (Nox2)-Containing NAD(P)H Oxidase in Angiogenesis in Response to Hindlimb Ischemia Circulation, May 10, 2005; 111(18): 2347 - 2355. [Abstract] [Full Text] [PDF] |
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M. Mayr, B. Metzler, Y.-L. Chung, E. McGregor, U. Mayr, H. Troy, Y. Hu, M. Leitges, O. Pachinger, J. R. Griffiths, et al. Ischemic preconditioning exaggerates cardiac damage in PKC-{delta} null mice Am J Physiol Heart Circ Physiol, August 1, 2004; 287(2): H946 - H956. [Abstract] [Full Text] [PDF] |
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C.J Zuurbier, O Eerbeek, P.T Goedhart, E.A Struys, N.M Verhoeven, C Jakobs, and C Ince Inhibition of the pentose phosphate pathway decreases ischemia-reperfusion-induced creatine kinase release in the heart Cardiovasc Res, April 1, 2004; 62(1): 145 - 153. [Abstract] [Full Text] [PDF] |
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W. Gu, D. Weihrauch, K. Tanaka, J. P. Tessmer, P. S. Pagel, J. R. Kersten, W. M. Chilian, and D. C. Warltier Reactive oxygen species are critical mediators of coronary collateral development in a canine model Am J Physiol Heart Circ Physiol, October 1, 2003; 285(4): H1582 - H1589. [Abstract] [Full Text] [PDF] |
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J. Minners, C. J. McLeod, and M. N. Sack Mitochondrial plasticity in classical ischemic preconditioning--moving beyond the mitochondrial KATP channel Cardiovasc Res, July 1, 2003; 59(1): 1 - 6. [Abstract] [Full Text] [PDF] |
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L. G. Kevin, A. K. S. Camara, M. L. Riess, E. Novalija, and D. F. Stowe Ischemic preconditioning alters real-time measure of O2 radicals in intact hearts with ischemia and reperfusion Am J Physiol Heart Circ Physiol, February 1, 2003; 284(2): H566 - H574. [Abstract] [Full Text] [PDF] |
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G. Lebuffe, P. T. Schumacker, Z.-H. Shao, T. Anderson, H. Iwase, and T. L. Vanden Hoek ROS and NO trigger early preconditioning: relationship to mitochondrial KATP channel Am J Physiol Heart Circ Physiol, January 1, 2003; 284(1): H299 - H308. [Abstract] [Full Text] [PDF] |
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S. Hoshida, N. Yamashita, K. Otsu, and M. Hori The importance of manganese superoxide dismutase in delayed preconditioning: Involvement of reactive oxygen species and cytokines Cardiovasc Res, August 15, 2002; 55(3): 495 - 505. [Abstract] [Full Text] [PDF] |
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R. Schulz, M. V Cohen, M. Behrends, J. M Downey, and G. Heusch Signal transduction of ischemic preconditioning Cardiovasc Res, November 1, 2001; 52(2): 181 - 198. [Full Text] [PDF] |
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P. Eaton, D. J Hearse, and M. J Shattock Lipid hydroperoxide modification of proteins during myocardial ischaemia Cardiovasc Res, August 1, 2001; 51(2): 294 - 303. [Abstract] [Full Text] [PDF] |
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N. S. Dhalla, A. B. Elmoselhi, T. Hata, and N. Makino Status of myocardial antioxidants in ischemia-reperfusion injury Cardiovasc Res, August 18, 2000; 47(3): 446 - 456. [Abstract] [Full Text] [PDF] |
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T. L. V. Hoek, L. B. Becker, Z.-H. Shao, C.-Q. Li, and P. T. Schumacker Preconditioning in Cardiomyocytes Protects by Attenuating Oxidant Stress at Reperfusion Circ. Res., March 17, 2000; 86(5): 541 - 548. [Abstract] [Full Text] [PDF] |
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S. ZAHLER, C. KUPATT, and B. F. BECKER Endothelial preconditioning by transient oxidative stress reduces inflammatory responses of cultured endothelial cells to TNF-{alpha} FASEB J, March 1, 2000; 14(3): 555 - 564. [Abstract] [Full Text] |
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S. Takeo and Y. Nasa Role of energy metabolism in the preconditioned heart - a possible contribution of mitochondria Cardiovasc Res, July 1, 1999; 43(1): 32 - 43. [Abstract] [Full Text] [PDF] |
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N. Yamashita, S. Hoshida, K. Otsu, M. Asahi, T. Kuzuya, and M. Hori Exercise Provides Direct Biphasic Cardioprotection via Manganese Superoxide Dismutase Activation J. Exp. Med., June 7, 1999; 189(11): 1699 - 1706. [Abstract] [Full Text] [PDF] |
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T. D. Lockwood Redox-dependent and redox-independent subcomponents of protein degradation in perfused myocardium Am J Physiol Endocrinol Metab, May 1, 1999; 276(5): E945 - E954. [Abstract] [Full Text] [PDF] |
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P. Eaton, J.-M. Li, D. J. Hearse, and M. J. Shattock Formation of 4-hydroxy-2-nonenal-modified proteins in ischemic rat heart Am J Physiol Heart Circ Physiol, March 1, 1999; 276(3): H935 - H943. [Abstract] [Full Text] [PDF] |
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W. Chen, R. London, E. Murphy, and C. Steenbergen Regulation of the Ca2+ Gradient Across the Sarcoplasmic Reticulum in Perfused Rabbit Heart : A 19F Nuclear Magnetic Resonance Study Circ. Res., November 2, 1998; 83(9): 898 - 907. [Abstract] [Full Text] [PDF] |
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R. Zucchi, G. Yu, P. Galbani, M. Mariani, G. Ronca, and S. Ronca-Testoni Sulfhydryl Redox State Affects Susceptibility to Ischemia and Sarcoplasmic Reticulum Ca2+ Release in Rat Heart : Implications for Ischemic Preconditioning Circ. Res., November 2, 1998; 83(9): 908 - 915. [Abstract] [Full Text] [PDF] |
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D. W. Green, H. N. Murray, P. G. Sleph, F.-L. Wang, A. J. Baird, W. L. Rogers, and G. J. Grover Preconditioning in rat hearts is independent of mitochondrial F1F0 ATPase inhibition Am J Physiol Heart Circ Physiol, January 1, 1998; 274(1): H90 - H97. [Abstract] [Full Text] [PDF] |
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S. A. Gabel, H. R. Cross, R. E. London, C. Steenbergen, and E. Murphy Decreased intracellular pH is not due to increased H+ extrusion in preconditioned rat hearts Am J Physiol Heart Circ Physiol, November 1, 1997; 273(5): H2257 - H2262. [Abstract] [Full Text] [PDF] |
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I. Tritto, D. D'Andrea, N. Eramo, A. Scognamiglio, C. De Simone, A. Violante, A. Esposito, M. Chiariello, and G. Ambrosio Oxygen Radicals Can Induce Preconditioning in Rabbit Hearts Circ. Res., May 19, 1997; 80(5): 743 - 748. [Abstract] [Full Text] |
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K. R. Laderoute and K. A. Webster Hypoxia/Reoxygenation Stimulates Jun Kinase Activity Through Redox Signaling in Cardiac Myocytes Circ. Res., March 1, 1997; 80(3): 336 - 344. [Abstract] [Full Text] |
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R. A. Forbes, C. Steenbergen, and E. Murphy Diazoxide-Induced Cardioprotection Requires Signaling Through a Redox-Sensitive Mechanism Circ. Res., April 27, 2001; 88(8): 802 - 809. [Abstract] [Full Text] [PDF] |
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D. X. Zhang, Y.-F. Chen, W. B. Campbell, A.-P. Zou, G. J. Gross, and P.-L. Li Characteristics and Superoxide-Induced Activation of Reconstituted Myocardial Mitochondrial ATP-Sensitive Potassium Channels Circ. Res., December 7, 2001; 89(12): 1177 - 1183. [Abstract] [Full Text] [PDF] |
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