Integrative Physiology |
From the Departments of Cardiovascular Medicine (H.T., T.I., S.H., N.S., A.T.), Clinical Chemistry and Laboratory Medicine (D.K., N.H.), and Developmental Molecular Anatomy (K.N.), Graduate School of Medical Sciences and the Department of Biophysics, Faculty of Pharmaceutical Sciences (H.U.), Kyushu University, Fukuoka, Japan.
Correspondence to Hiroyuki Tsutsui, MD, PhD, Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. E-mail prehiro{at}cardiol.med.kyushu-u.ac.jp
| Abstract |
|---|
|
|
|---|
Key Words: mitochondria free radicals heart failure myocardial infarction remodeling
| Introduction |
|---|
|
|
|---|
ROS can damage various cellular components, such as proteins, lipids, and DNAs. They can damage mitochondrial macromolecules either at or near the site of their formation. Therefore, in addition to the role of mitochondria as a source of ROS, the mitochondria themselves can be damaged by ROS.6 7 Mitochondrial injury is reflected by mitochondrial DNA (mtDNA) damage as well as by a decline in the mitochondrial RNA (mtRNA) transcripts, protein synthesis, and mitochondrial function. mtDNA is more susceptible to oxidative attack than nuclear DNA, possibly because of its proximity to the respiratory chain in the mitochondrial inner membrane, the lack of protective histone-like proteins, and its poor repair activity against damage.8 mtDNA mutations may prevent its replication or expression. Therefore, mitochondrial ROS may result in the progressive destruction of the mtDNA, and such mtDNA damage can lead to a decline of mtRNA transcription and a loss of function.9 Recent in vitro studies have clearly shown that ROS mediate mtDNA damage, alterations of gene expression, and mitochondrial dysfunction in cultured vascular endothelial and smooth muscle cells.10
Mitochondria contain closed circular, double-stranded DNA of
16.5 kb. Both strands of the mtDNA are transcribed. The
mitochondrial genome encodes 13 polypeptides involved in oxidative
phosphorylation, including 7 subunits (ND1, ND2, ND3, ND4, ND4L, ND5,
and ND6) of rotenone-sensitive NADH-ubiquinone oxidoreductase (complex
I), 1 subunit (cytochrome b) of
ubiquinol-cytochrome c
oxidoreductase (complex III), 3 subunits (COI, COII, and COIII) of
cytochrome c oxidase (complex
IV), and 2 subunits (ATPases 6 and 8) of complex V along with 22 tRNA
and 2 rRNA (12S and 16S) subunits. The polypeptides are translated by
mitochondrial ribosomes and consist of components of the electron
transport chain.8 As opposed
to nuclear-encoded genes, mitochondrial-encoded gene expression is
largely regulated by the copy number of
mtDNA.11 A decrease in the
mtDNA copy number results in a corresponding decrease in mtRNA and
proteins, finally leading to mitochondrial dysfunction.
We thus hypothesized that mtDNA, mtRNA, and proteins all decrease in failing mitochondria, in which higher levels of ROS are produced. Therefore, the objective of the present study was to measure the amount of ROS using ESR techniques and to examine the changes in the mtDNA copy number and the steady-state content of mtRNA transcripts as well as the activity of the electron transport chain complex enzymes in failing hearts. In the present study, we used a murine model of myocardial infarction (MI) after a coronary artery ligation for 4 weeks, in which the LV cavity was dilated and contractility was reduced.4
| Materials and Methods |
|---|
|
|
|---|
Echocardiography
On the day the study was terminated, 4 weeks after
surgery, one subset of investigators (S.H. and N.S.), who were not
informed of the experimental groups, performed echocardiographic
studies.4
Myocardial Tissue Preparation
The myocardial tissue specimens with MI were
carefully dissected into two parts, one consisting of the infarcted LV
with the peri-infarct rim (a 0.5- to 1-mm rim of normal-appearing
tissue), and the remaining consisting of noninfarcted (remote) LV. In
all subsequent assays, the comparison was made between noninfarcted LV
myocardium from MI animals and control LV myocardium from sham-operated
animals.
Myocardial ROS
ROS were quantified in the LV by using ESR
spectroscopy with
4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl
(hydroxy-TEMPO).5
Mitochondrial TBARS
The formation of lipid peroxides was measured in the
mitochondrial fraction isolated from LV myocardium through a
biochemical assay of
TBARS.1
Myocardial Biochemical Measurements
The myocardial content of DNA, RNA, and protein was
measured and expressed as mg/g wet
weight.15 To determine
whether quantitative changes in specific contractile protein content
occur with MI, an electrophoretic separation of myocardial protein
homogenates was performed.
DNA Isolation and Southern Blot Analysis of
mtDNA
DNA was extracted from LV, and a Southern blot
analysis was performed to measure the mtDNA copy
number.12 13
Primers for the mtDNA probe corresponded to nucleotides 24243605 of
the mouse mitochondrial genome, and those for the nuclear-encoded mouse
18S rRNA probe corresponded to nucleotides 4351951 of the human 18S
rRNA genome. The mtDNA levels were normalized to the abundance of the
18S rRNA gene run on the same gel. The protein levels of transcription
factor A (Tfam), a nucleus-coded protein with the capacity to recognize
and bind to specific mtDNA sequences, were analyzed by Western blot
analysis.13
RNA Isolation and Northern Blot
Analysis
Total RNA was isolated from frozen LV by the
guanidinium method, and a Northern hybridization analysis was
performed.14 Probes for
mtRNA analysis were prepared by amplification of nucleotides 12092606
(probe 1), nucleotides 33517570 (probe 2), nucleotides 886114549
(probe 3), and nucleotides 1472915837 (probe 4) of mtDNA from mouse
genomic DNA
(Figure 1
). In addition, the mRNA levels for the contractile
proteins, including cardiac
-actin and myosin heavy chain, as well
as mitochondrial proteins, such as manganese superoxide dismutase
(MnSOD), all of which are coded by nuclear DNA, were also measured in
the LVs from both groups.
|
Mitochondrial Enzyme Activity
The specific activity of mitochondrial complex
enzymes, including complexes I, II, III, and IV, was measured in the
LV. The activity of citrate synthase, one of nuclear DNA-coded
mitochondrial enzymes, was also measured.
Myocardial Structure
The coronal sections from mid-LV were fixed in 6%
formaldehyde, and 5-µm-thick paraffin-embedded sections were stained
with Massons trichrome. The mitochondrial ultrastructure was assessed
by electron
microscopy.16 17
An expanded Materials and Methods section can be found in an online data supplement available at http://www.circresaha.org.
| Results |
|---|
|
|
|---|
Oxidative Stress in the Mitochondria
ESR signals of hydroxy-TEMPO decreased more rapidly in
the presence of myocardial homogenates from MI hearts compared with
sham
(Figure 2A
). There was a linear relation in the
semilogarithmic plot of peak signal intensity versus time, thus
indicating the first order kinetics of the signal decay
(Figure 2B
). The rate constant of signal decay, calculated
from the slope of this line, was significantly larger in MI than that
in sham mice
(Figure 2C
). DMTU (50 mmol/L) added to the reaction mixture
completely abolished an increase of signal decay in MI, indicating that
OH· contributed to this increase
(Figure 2C
). SOD (50 U/mL) plus catalase (50 U/mL) also
attenuated an increased signal decay rate in MI, which implies the
contribution of
O2-· to the
production of OH·. These results confirmed
our recent results that
O2-· and
OH· increased in the LV from MI
mice.4
|
MI mice had a 4-fold increase in TBARS formation in the mitochondrial fraction compared with sham-operated animals (2.7±0.9 versus 11.4±2.4 nmol/mg mitochondrial protein, P<0.01), thus indicating enhanced lipid peroxidation.
Myocardial Biochemical Composition
The biochemical composition of LV from the sham and MI
groups is shown in online Table 2. In the MI mice, no significant
change was observed in the myocardial DNA, RNA, or protein content
compared with sham mice. The quantification of actin revealed no
significant change in the LV after MI
(Figure 3
and online Table 2).
|
mtDNA Copy Number and mtRNA Expression
The copy number of mtDNA, expressed as the ratio of
mtDNA to nuclear DNA (18S rRNA), as measured by a Southern blot
analysis, decreased by 44%
(P<0.05) in MI compared with
sham mice (1.03±0.02 versus 0.58±0.13;
Figure 3
). Parallel to the mtDNA copy number, the Tfam
protein level also decreased by 35% in MI animals (148±9 versus
96±6, P<0.05).
To determine the effects of a decreased mtDNA copy number on
mtRNA, mtRNA transcript levels were measured by Northern blot analysis.
MI showed a significant decrease in ND1+ND2, ND4, ND4L, ND5, cytochrome
b, COI, COII, and COIII
transcripts as well as 16S rRNA
(Figure 4
). In contrast, the steady-state mRNA levels for
cardiac
-actin were virtually identical between the sham and MI mice
(63.4±5.9 versus 51.4±5.6,
P=NS;
Figure 4
). Similarly, myosin heavy chain mRNA levels were
comparable between the groups (125.2±13.5 versus 102.0±19,3
P=NS). Furthermore, the MnSOD
mRNA level was also comparable (68.7±3.3 versus 71.4±3.4,
P=NS). As a result, all
mitochondrial mRNAs tested were downregulated by 30% to 50% in MI
(Figure 5
), whereas the mRNA levels for the nucleus-coded
mRNA levels remained unchanged.
|
|
Mitochondrial Enzymes
Having demonstrated that the mtRNA levels are
downregulated in MI, the enzymatic activity of the mitochondria was
quantified
(Figure 6
). The enzymatic activities of complexes I, III, and
IV all decreased in MI. In contrast, there was no decrease in the
enzymatic activity of complex II and citrate synthase in MI, both of
which were exclusively encoded by nuclear DNA.
|
Myocardial Structure
A light microscopic analysis of myocardial tissue
sections has indeed shown increased interstitial fibrosis in MI.
However,
90% to 95% of all cross sections were occupied by cardiac
myocytes in either the sham or MI mice
(Figure 7
).
|
We detected no evidence of myocyte injury in MI at an
ultrastructural level
(Figure 7
). Myofibrillar organization was maintained, and the
membrane structure was preserved at the sarcolemma. In both the sham
and MI myocytes, the mitochondria were present throughout the cytoplasm
in a characteristic organized pattern around the Z line. The sarcomere
(sm) length was comparable between sham and MI myocytes (1.59±0.03
versus 1.65±0.03 µm; P=NS).
However, the overall number of interfibrillar mitochondria increased in
MI compared with sham mice (117±14 versus 149±9/100
sm2;
P<0.05), and the overall
average size of the mitochondria decreased in MI (0.59±0.04 versus
0.45±0.03 µm2;
P<0.05).
| Discussion |
|---|
|
|
|---|
Mitochondrial Oxidative Stress
The production of ROS increased in the noninfarcted LV,
which was originated from
O2-·
(Figure 2
). An increased generation of ROS was associated
with a concomitant increase in the oxidation of lipids in the
mitochondria. These results are consistent with our previous studies in
a canine model of HF attributable to rapid ventricular
pacing.1 5
mtDNA Damage
The present results showed that the mtDNA copy number
is decreased in the post-MI failing myocardium, whereas nuclear DNA is
less affected
(Figure 3
). Even though we could not rule out the possibility
of dilutional effects by the proliferation of nonmyocytes, including
fibroblasts and endothelial cells, on our measures of mtDNA, mtRNA, and
enzyme activities, a relative loss of myocytes to nonmyocytes is not
sufficient to explain the magnitude of the decline in mtDNA and mtRNA
in MI for several reasons. First, the combination of a biochemical
analysis of myocardial composition (online Table 2, available at
http://www.circresaha.org) and a morphological analysis of the
myocardial structure
(Figure 7
) indicated that myocyte loss was not prominent in
the noninfarcted LV. Second, the amount of Tfam protein that binds to
mtDNA concurrently decreased. Third, the mRNA levels for contractile
proteins did not change in MI. Fourth, nucleus-coded mitochondrial
proteins, such as MnSOD and citrate synthase, did not decrease in MI.
Fifth, when separating noninfarcted and infarcted tissues, we took
special care not to include the peri-infarct tissue in the
sample.
Furthermore, the decline in mtDNA copy number was not
attributable to the defects of mitochondrial biogenesis, because an
electron micrographic analysis showed that the number of mitochondria
increased, and did not decrease, in the MI hearts
(Figure 7
). Therefore, the number of mitochondrial genomes
per mitochondria must be even lower. A decreased mtDNA copy number is
responsible for mitochondrial dysfunction, because the maintenance of
mtDNA is essential for maintaining the expression of proteins. In fact,
a decrease in the mtDNA copy number has been implicated in the
pathogenesis of mitochondrial diseases and zidovudine-induced
myopathy.18 19
Even though the mechanisms controlling the mtDNA copy number are still poorly understood, mtDNA depletion may result from a ROS-induced mutation at the origins of replication. In addition, a mutation outside the origins of replication is capable of interfering with replication.18 It is conceivable to speculate that the mtDNA could be a major target for ROS-mediated damage for several reasons. First, mitochondria do not have a complex chromatin organization consisting of histone proteins, which may serve as a protective barrier against ROS. Second, mtDNA has a limited repair activity against DNA damage. Third, a large part of O2-·, which is formed inside the mitochondria, cannot pass through the membranes and, hence, ROS damage may be contained largely within the mitochondria. In fact, mtDNA accumulates significantly higher levels of DNA oxidation product, 8-hydroxydeoxyguanosine, than nuclear DNA does.20
Mitochondrial Dysfunction
Parallel to the decrease in the mtDNA copy number; ie,
mitochondrial template availability, the mtRNA transcript levels also
decreased in MI
(Figures 4
and 5
). The significance of these findings is
additionally amplified in the absence of any changes in the expression
of nuclear-derived transcripts
(Figure 4
). Interestingly, a Northern blot analysis showed a
similar extent of decrease in all of the mtRNAs examined
(Figure 5
). In agreement with previous
studies,11 these results
indicate that the decrease in mitochondrial transcription could be
explained by the decrease in the mtDNA copy number, and thus no changes
in either the transcriptional or translational efficiencies are
required.
Consistent with alterations in the mtDNA and transcript
levels, the oxidative capacities decreased in MI
(Figure 6
). Importantly, the enzymatic activity of complex II
and citrate synthase was not affected, because it is entirely encoded
by nuclear DNA, whereas the activity of complexes I, III, and IV, which
are partially encoded by the mtDNA genes, was significantly lower in
the post-MI hearts
(Figure 6
). Our data thus imply a relationship between a
decreased mtDNA copy number and an impaired mitochondrial function,
because the magnitude of the mtDNA defects is parallel to quantitative
deficiencies in the mtRNA transcripts and electron transport chain
function.
Previous studies have suggested an intimate link between mtDNA damage, increased lipid peroxidation, and a decrease in complex enzyme activities.9 In fact, Tfam knockout mice, which had a 50% reduction in their transcript and protein levels, exerted a 34% reduction in the mtDNA copy number, 22% reduction in the mitochondrial transcript levels, and partial reduction in the cytochrome c oxidase levels in the heart.13 Furthermore, recent studies using cultured vascular endothelial and smooth muscle cells have clearly demonstrated that ROS can cause mtDNA damage, altered mitochondrial gene expression, and dysfunction.10 Nevertheless, the present observations do not allow us to establish a meaningful mechanistic link between ROS and the mtDNA defects in MI. To establish a cause-and-effect relationship between these cellular events, time-dependent changes in ROS, mtDNA, and mitochondrial function should be clarified during the development of postinfarct HF. Additionally, it would be significant to determine whether the direct exposure of cardiac myocytes to ROS results in mtDNA depletion.
Even though the mitochondrial respiration data were not
available in our animals, previous studies have shown that the
enzymological abnormalities of the respiratory chain are consistent
with the functional
defects.21 The decreased
mitochondrial transcript levels and enzymatic activities are intriguing
in their implication that the decline of mtDNA is associated with
oxidative stress and can lead to mitochondrial dysfunction. Presumably,
mitochondrial template depletion may result in its functional decline,
which additionally exacerbates the defects of electron transport and
produces ROS
(Figure 8
).5 In
addition, ROS can directly damage complex enzymes, because they consist
of iron-sulfur clusters that can be inactivated by
O2-·.
|
Clinical Implications
Several pathogenic mtDNA base substitution mutations,
such as missense mutations and mtDNA rearrangement mutations (deletions
and insertions), have been identified in patients with mitochondrial
diseases.9 An accumulation of
the deleted forms of mtDNA in the myocardium frequently results in
either cardiac hypertrophy, conduction block, or
HF.22 Furthermore, there is
now a consensus view that mutations in mtDNA and abnormalities in
mitochondrial function are associated with common forms of cardiac
diseases, such as ischemic heart
disease23 and dilated
cardiomyopathy.24 In these
conditions, however, the strict causal relationships between
abnormalities in mtDNA and cardiac dysfunction have yet to be fully
elucidated.25 Even though
the mechanisms by which mtDNA damage arises in these conditions have
not been clarified, ROS have been proposed to be the primary
contributing factor. In the present study, we provided direct evidence
that mtDNA defects occur not only in a limited small subset of
mitochondrial diseases but also in a more common HF phenotype occurring
after MI in mice. In addition, these alterations in mtDNA and
mitochondrial function may also result from oxidative stress. The
present findings are also supported by the studies on mice lacking
MnSOD, which show an accumulation of oxidative damage of mtDNAs and
electron transport
complexes21 in association
with the development of dilated
cardiomyopathy.26
The remodeling of noninfarcted LV is characterized by myocyte hypertrophy and interstitial fibrosis, both of which are also recognized in pressure-overloaded cardiac hypertrophy. Therefore, we could not rule out the possibility that the similar alterations in mtDNA and electron transport complexes could be observed in hypertrophied hearts in general, especially because increased ROS generation has been demonstrated in an animal model of cardiac hypertrophy.3
Conclusions
The present study demonstrates that chronic increases
in ROS production are associated with mitochondrial damage and
dysfunction, which thus lead to a catastrophic cycle of mitochondrial
functional decline, additional ROS generation, and cellular injury.
Therefore, these cellular events might be involved in myocardial
remodeling and
failure.
| Acknowledgments |
|---|
| Footnotes |
|---|
1 Both authors contributed equally to this study. ![]()
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
A. K. Doughan, D. G. Harrison, and S. I. Dikalov Molecular Mechanisms of Angiotensin II-Mediated Mitochondrial Dysfunction: Linking Mitochondrial Oxidative Damage and Vascular Endothelial Dysfunction Circ. Res., February 29, 2008; 102(4): 488 - 496. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. B. Gustafsson and R. A. Gottlieb Heart mitochondria: gates of life and death Cardiovasc Res, January 15, 2008; 77(2): 334 - 343. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. H. George Sarcoplasmic reticulum Ca2+ leak in heart failure: mere observation or functional relevance? Cardiovasc Res, January 15, 2008; 77(2): 302 - 314. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. M. Redout, M. J. Wagner, M. J. Zuidwijk, C. Boer, R. J.P. Musters, C. van Hardeveld, W. J. Paulus, and W. S. Simonides Right-ventricular failure is associated with increased mitochondrial complex II activity and production of reactive oxygen species Cardiovasc Res, September 1, 2007; 75(4): 770 - 781. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Seddon, Y. H Looi, and A. M Shah Oxidative stress and redox signalling in cardiac hypertrophy and heart failure Heart, August 1, 2007; 93(8): 903 - 907. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. C. Sparagna, A. J. Chicco, R. C. Murphy, M. R. Bristow, C. A. Johnson, M. L. Rees, M. L. Maxey, S. A. McCune, and R. L. Moore Loss of cardiac tetralinoleoyl cardiolipin in human and experimental heart failure J. Lipid Res., July 1, 2007; 48(7): 1559 - 1570. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Srivastava, B. Chandrasekar, Y. Gu, J. Luo, T. Hamid, B. G. Hill, and S. D. Prabhu Downregulation of CuZn-superoxide dismutase contributes to {beta}-adrenergic receptor-mediated oxidative stress in the heart Cardiovasc Res, June 1, 2007; 74(3): 445 - 455. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Doerries, K. Grote, D. Hilfiker-Kleiner, M. Luchtefeld, A. Schaefer, S. M. Holland, S. Sorrentino, C. Manes, B. Schieffer, H. Drexler, et al. Critical Role of the NAD(P)H Oxidase Subunit p47phox for Left Ventricular Remodeling/Dysfunction and Survival After Myocardial Infarction Circ. Res., March 30, 2007; 100(6): 894 - 903. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Neubauer The Failing Heart -- An Engine Out of Fuel N. Engl. J. Med., March 15, 2007; 356(11): 1140 - 1151. [Full Text] [PDF] |
||||
![]() |
J. H. Rennison, T. A. McElfresh, I. C. Okere, E. J. Vazquez, H. V. Patel, A. B. Foster, K. K. Patel, Q. Chen, B. D. Hoit, K.-Y. Tserng, et al. High-fat diet postinfarction enhances mitochondrial function and does not exacerbate left ventricular dysfunction Am J Physiol Heart Circ Physiol, March 1, 2007; 292(3): H1498 - H1506. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. C. Spikings, J. Alderson, and J. C. St. John Regulated Mitochondrial DNA Replication During Oocyte Maturation Is Essential for Successful Porcine Embryonic Development Biol Reprod, February 1, 2007; 76(2): 327 - 335. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Takimoto and D. A. Kass Role of Oxidative Stress in Cardiac Hypertrophy and Remodeling Hypertension, February 1, 2007; 49(2): 241 - 248. [Full Text] [PDF] |
||||
![]() |
H. Nojiri, T. Shimizu, M. Funakoshi, O. Yamaguchi, H. Zhou, S. Kawakami, Y. Ohta, M. Sami, T. Tachibana, H. Ishikawa, et al. Oxidative Stress Causes Heart Failure with Impaired Mitochondrial Respiration J. Biol. Chem., November 3, 2006; 281(44): 33789 - 33801. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. E. Murdoch, M. Zhang, A. C. Cave, and A. M. Shah NADPH oxidase-dependent redox signalling in cardiac hypertrophy, remodelling and failure Cardiovasc Res, July 15, 2006; 71(2): 208 - 215. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Wang, T. Miura, N. Harada, R. Kametani, M. Shibuya, Y. Fukagawa, S. Kawamura, Y. Ikeda, M. Hara, and M. Matsuzaki Pleiotropic Effects of the beta-Adrenoceptor Blocker Carvedilol on Calcium Regulation during Oxidative Stress-Induced Apoptosis in Cardiomyocytes J. Pharmacol. Exp. Ther., July 1, 2006; 318(1): 45 - 52. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. Petermann, C. Mayer, J. Stypmann, M. L. Biniossek, D. J. Tobin, M. A. Engelen, T. Dandekar, T. Grune, L. Schild, C. Peters, et al. Lysosomal, cytoskeletal, and metabolic alterations in cardiomyopathy of cathepsin L knockout mice FASEB J, June 1, 2006; 20(8): 1266 - 1268. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Matsushima, T. Ide, M. Yamato, H. Matsusaka, F. Hattori, M. Ikeuchi, T. Kubota, K. Sunagawa, Y. Hasegawa, T. Kurihara, et al. Overexpression of Mitochondrial Peroxiredoxin-3 Prevents Left Ventricular Remodeling and Failure After Myocardial Infarction in Mice Circulation, April 11, 2006; 113(14): 1779 - 1786. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. J. Grieve, J. A. Byrne, A. Siva, J. Layland, S. Johar, A. C. Cave, and A. M. Shah Involvement of the Nicotinamide Adenosine Dinucleotide Phosphate Oxidase Isoform Nox2 in Cardiac Contractile Dysfunction Occurring in Response to Pressure Overload J. Am. Coll. Cardiol., February 21, 2006; 47(4): 817 - 826. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Mollnau, M. Oelze, M. August, M. Wendt, A. Daiber, E. Schulz, S. Baldus, A. L. Kleschyov, A. Materne, P. Wenzel, et al. Mechanisms of Increased Vascular Superoxide Production in an Experimental Model of Idiopathic Dilated Cardiomyopathy Arterioscler. Thromb. Vasc. Biol., December 1, 2005; 25(12): 2554 - 2559. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Nimata, T.-a. Okabe, M. Hattori, Z. Yuan, K. Shioji, and C. Kishimoto MCI-186 (edaravone), a novel free radical scavenger, protects against acute autoimmune myocarditis in rats Am J Physiol Heart Circ Physiol, December 1, 2005; 289(6): H2514 - H2518. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. G. Kevin, E. Novalija, and D. F. Stowe Reactive Oxygen Species as Mediators of Cardiac Injury and Protection: The Relevance to Anesthesia Practice Anesth. Analg., November 1, 2005; 101(5): 1275 - 1287. [Abstract] [Full Text] [PDF] |
||||
![]() |