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Vol. 302, Issue 3, 1123-1128, September 2002
Departments of Anesthesia and Perioperative Care (C.U.N.), Radiology (M.S., H.A.), and Biopharmaceutical Sciences (W.J., L.Z.B., U.C., N.S.), University of California, San Francisco, California; Department of Anesthesiology (W.J., U.C., N.S.), University of Colorado Health Sciences Center, Denver, Colorado; and Department of Biology/Chemistry (N.S.), Universität Bremen, Bremen, Germany
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Abstract |
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 Top
 Abstract
 Introduction
Materials and Methods
Results
Discussion
References
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Cyclosporine protects the heart against ischemia/reperfusion injury,
but its effect on cardiac metabolism is largely unknown. We assessed
cyclosporine-induced metabolic changes in the rat heart prior to
occlusion using magnetic resonance spectroscopy (MRS) and correlated
effects with infarct size in a coronary occlusion/reperfusion model.
The two study groups were cyclosporine and cyclosporine + coronary
occlusion (n = 20/group). Rats were pretreated with cyclosporine (5, 10, 15, and 25 mg/kg/day) or the vehicle by oral gavage for 3 days (n = 4/dose). On day 4, hearts of
rats in the cyclosporine group were excised, and extracted cell
metabolites were measured using 1H and 31P MRS.
The second group was subjected to 30 min of coronary artery occlusion
followed by 24 h of reperfusion. Infarct size and area at risk
were measured using a double staining method. In the cyclosporine group, cyclosporine reduced cardiac energy metabolism (ATP:
r = 
0.89, P < 0.001) via
depression of oxidative phosphorylation and the Krebs' cycle in a
dose-dependent manner. The decrease of ATP levels was positively
correlated with changes of NAD+ (r = 0.89), glutamate (r = 0.95), glutamine
(r = 0.84), and glucose concentrations
(r = 0.92, all P < 0.002). It
was inversely correlated with lactate (r = 0.93,
P < 0.001). In the coronary occlusion group,
cyclosporine dose dependently reduced the ratio [area of infarct/area
of the left ventricle] (r = 0.86,
P < 0.01), with 15 mg/kg/day being the most
effective cyclosporine dose. The reduction in infarct size correlated
with the reduction in oxidative phosphorylation (ATP:
r = 0.97; NAD+: r = 0.82, P < 0.01). The reduction in cardiac energy
metabolism before occlusion may be the cause of myocardial preservation
during ischemia/reperfusion.
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Introduction |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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The
calcineurin inhibitor cyclosporine has been widely used as an
immunosuppressant after organ transplantation (Kahan, 1989
) and for the
treatment of immune diseases (Faulds et al., 1993) for more than 2 decades. However, its clinical use is limited by a narrow therapeutic
index and toxicity, mainly to kidney, liver, and the central nervous
and cardiovascular systems (Kahan, 1989). Recent studies have indicated
that cyclosporine significantly inhibits energy metabolism in brain
(Serkova et al., 2001, 2002), kidney (Henke et al., 1992), and liver
(Zhong et al., 2001), all primary target organs of cyclosporine
toxicity. Although cyclosporine causes neurotoxicity (Kahan, 1989;
Gijtenbeek et al., 1999) and was shown to significantly inhibit brain
mitochondrial energy metabolism under normoxic conditions (Serkova et
al., 2001), paradoxically, cyclosporine protects mitochondrial energy
metabolism during ischemia and reperfusion in cell cultures and animal
models (Uchino et al., 1998; Serkova et al., 2002). Although a
substantial effort has been made to assess the neuroprotective effects
of cyclosporine against stroke, only relatively few reports have
evaluated the potential of cyclosporine to prevent ischemic/reperfusion
damage in other organs, such as the heart. This is surprising since
cyclosporine only poorly penetrates the blood-brain barrier, limiting
its clinical application as a neuroprotective agent (Begley et al.,
1990).
Recently, it has been shown that cyclosporine readily distributes into
cardiac tissue, reaching concentrations greater than in blood (Serkova
et al., 2000). Previous in situ and in vitro studies have suggested
that cyclosporine has both detrimental and beneficial effects on the
heart (Paul et al., 1991, 1992; Tatou et al., 1996; Rao et al., 1998;
Park et al., 1999). For example, cyclosporine may protect the heart
against toxicity of drugs such as doxorubicin (Adriamycin) and
cyclophosphamide (Al-Nasser, 1998a,b), prevent cardiac hypertrophy
(Force et al., 1999), and diminish ischemia/reperfusion injury
(Griffiths and Halestrap, 1993; Halestrap et al., 1997; Massoudy et
al., 1997; Weinbrenner et al., 1998; Squadrito et al., 1999). As of
today, the changes of myocardial cell metabolism caused by cyclosporine
under normoxic conditions have not yet been described in detail. If, as
in the brain, cyclosporine reduces mitochondrial oxidative energy
production prior to cardiac occlusion, it could have a significant
impact on ischemia/reperfusion injury in the infarcted heart. It has been previously shown that depletion of energy sources prior to cardiac
ischemia produces physiological preconditioning, which is beneficial
for postischemic outcome (Murry et al., 1986; Garnier et al., 1996). It
was our goal to study the effects of cyclosporine on cardiac metabolism
in vivo using magnetic resonance spectroscopy (MRS) to determine
whether there is any correlation between the infarct size and the
status of cardiac metabolism, and to find the optimum cyclosporine dose
for cardiac protection against ischemia/reperfusion injury.
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Materials and Methods |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Experimental Design. All animal protocols were reviewed and approved by the University of California, San Francisco, Committee on Animal Research, and animal care was in agreement with the National Institutes of Health guidelines for ethical animal research (National Institutes of Health publication 80-123, revised 1985). For our studies, we used young adult male Sprague-Dawley rats (6 months old). Body weight (280-320 g) was monitored daily, and no change occurred during the cyclosporine treatment. Rats were randomly assigned to two groups of cyclosporine and cyclosporine + coronary occlusion (n = 20/group). In both groups, cyclosporine (doses 0, 5, 10, 15, and 25 mg/kg/day, n = 4) was administered as its Neoral formulation (Novartis Pharma AG, Basel, Switzerland) diluted in milk by daily oral gavage for 3 days.
Effect of Cyclosporine on Cardiac Energy Metabolism.
To
assess cyclosporine-induced metabolic changes, we quantified key cell
metabolites in perchloric acid (PCA) and lipid extracts using MRS. On
day 4, 4 h after the last cyclosporine dose, rats were
anesthetized, and the beating hearts were excised and immediately frozen in liquid nitrogen. Frozen hearts were weighed, homogenized in a
mortar grinder in the presence of liquid nitrogen, and extracted with 4 ml of ice-cold PCA (12%) as described in detail by Serkova et al.
(2001). For each extract, 1 g of heart tissue was used. The
samples were centrifuged, the aqueous phase was removed, and the
samples were neutralized using KOH and centrifuged once again. The
lipid fraction was extracted from the pellets remaining after the
aqueous extraction step. The pellets were dissolved in 4 ml of ice-cold
water, and the solution was neutralized. Both the aqueous extract and
the redissolved pellet were lyophilized overnight. The lyophilisates of
the aqueous extracts were redissolved in 0.45 ml of deuterium oxide
(D2O) and adjusted to pH 7 using DCl and NaOD.
The lipid fraction was extracted from the lyophilisates of the
redissolved pellet by the addition of 1 ml of deuterated chloroform/methanol mixture
(CDCl3/CD3OD; 2:1 v/v).
After centrifugation, the supernatants were analyzed by MRS.
). In
brief, all one-dimensional MR spectra of tissue PCA aqueous and lipid
extracts were recorded on a Bruker AMX 360 spectrometer and processed
using WINNMR software (Bruker, Karlsruhe, Germany). A 5-mm
1HX-inverse probe was used for all experiments.
For proton MRS, the operating frequency was 360 MHz, and a standard
presaturation pulse program was used for water suppression. The other
parameters were 40 accumulations, 90° pulse angle, 0-dB power level,
7.35 µs of pulse width, 10 ppm of spectral width, and 12.85 s of
repetition time. Trimethylsilyl
propionic-2,2,3,3,-d4 acid (0.6 mmol/l) was used as an external standard for the quantification of
metabolites based on 1H MR spectra.
1H chemical shifts of spectra were referenced to
trimethylsilyl propionic-2,2,3,3,-d4
acid at 0 ppm. For 31P MRS analysis of PCA
extracts, 100 mmol/l EDTA were added for complexation of divalent ions,
resulting in significantly narrower line width of
31P peaks. The pH was adjusted to 7 using KOH and
HCl. The following NMR parameters with a composite pulse
decoupling program were used: 145.7-MHz operating
31P frequency, 800 accumulations, 90° pulse
angle, 12-dB power level for 31P channel, 9 µs
of pulse width, 35 ppm of spectral width, and 2.0 s of repetition
time. The chemical shift of phosphocreatine at 2.33 ppm was used as a
shift reference. The absolute concentrations of phosphocreatine
calculated from 1H MRS were used for metabolite
quantification of 31P MR spectra.
In addition, lipid peroxidation (LPO) was measured in cardiac tissues
using the malondialdehyde/thiobarbituric acid (TBA) test (Mihara and
Uchiyama, 1978). Three hundred fifty µl of tissue homogenate (100 mg/100 ml extraction buffer) were added to a solution containing 15 mM
SDS, 1 mM EGTA, 2.25 mM butylated hydroxytoluene, and 20 mM 2-TBA.
Twenty percent acetic acid (pH adjusted with NaOH to 3.5) was added,
resulting in a final volume of 2 ml. The reaction mixture was incubated
for 60 min at 95°C. After cooling to 0°C, 2 ml of butanol/pyridine
(1:1 v/v) were added, and the solution was shaken vigorously and then
centrifuged at 4000 rpm for 5 min. The organic phase was used to
measure absorption in a photometer at 532 nm or fluorescence with
excitation set to 515 nm and emission set to 555 nm.
1,1,3,3-Tetraethoxypropan was used as a standard.
Effect of Cyclosporine on Infarct Size in Rats after Coronary Occlusion and Reperfusion. On day 4, 4 h after the last cyclosporine dose, rats in the cyclosporine + coronary occlusion group were subjected to 30 min of coronary artery occlusion followed by 24 h of reperfusion. The rats were anesthetized with a single dose of 50 mg/kg ketamine and 1.4 mg/kg xylazine injected intraperitoneally. The trachea was exposed, and a tracheotomy was performed. The rats were ventilated using a constant-volume ventilator with a volume of 1 to 2 ml/100 g of body weight at a rate of 65 to 70 strokes/min. The chest was opened through the fourth intercostal space. The pericardium was opened, and the main branch of the left coronary artery was occluded for 30 min 1 to 2 mm below the left atrial appendage by an intramural stitch with a 6.0 polypropylene suture. Subsequently, the suture was removed and the chest was closed; the animals were allowed to recover from anesthesia. Animals were monitored for 2 h after completion of surgery.
After 24 h of reperfusion, the coronary artery was reoccluded, and 0.2 ml of phthalocyanine blue dye was injected into the tail vein. This dye imparts a blue color to normally perfused myocardium, but the territory of the occluded artery (area at risk) remains unstained (Saeed et al., 1989). After the animal was sacrificed, the left
ventricle was transversely sliced into three 2-mm thick slices. Both
upper and lower surfaces of the stained three slices (apex, center, and
base of the left ventricle) were photographed with a flatbed scanner
connected to a computer and quantified. Then the three slices were
incubated in 2% triphenyltetrazolium chloride saline solution
for 8 min at 37°C. After 2% triphenyltetrazolium chloride staining
saline solution, viable myocardium stains brick red, whereas infarcted
regions stain pale white. Both faces of each slice were then
photographed again. Epicardial and endocardial contours of normal and
postischemic myocardium were traced manually. The fractions of area at
risk and infarct size to total slice surface area were measured by
planimetry from the two sets of photographs (Saeed et al., 1999).
Measurement of Cyclosporine Concentrations in Blood and Heart
Tissues.
At the time of sacrifice of the cyclosporine + coronary
occlusion group, blood samples (0.25 ml, anticoagulated with EDTA) and
cardiac tissue samples from the normally perfused heart, the area at
risk, and the infarcted area were collected. Samples were frozen in
liquid nitrogen and stored at 80°C until HPLC/MS analysis. All
samples were analyzed within 7 days after collection. For quantification of cyclosporine concentrations, an HPLC/electrospray-MS assay with automated on-line sample preparation by column-switching (LC/LC-MS) based on methods described previously (Christians et al.,
2000; Serkova et al., 2000) was used. In brief, heart tissue samples
were weighed and homogenized in 0.5 ml of
KH2PO4 buffer, pH 7.4 (1 M). For protein precipitation, 1 ml of methanol/1 M ZnSO4 (80:20 v/v) containing 100 µg/l internal
standard cyclosporine D was added to 0.25 ml of blood/tissue
homogenate. Samples were vortexed for 30 s and centrifuged at
10,000g for 10 min. One hundred microliters of the
supernatant were injected onto the 10.2-mm extraction column filled
with Hypersil ODS-1 of 10-µm particle size (Shandon Scientific,
Chadwick, UK). Automated sample preparation and analysis were carried
out using two HPLC systems (all series HP1100 components;
Hewlett-Packard, Palo Alto, CA) connected by a 7240 Rheodyne 6-port
switching valve mounted on a step motor (Rheodyne, Rohnert Park, CA).
Samples were washed with a 4:6 (v/v) mobile phase of methanol and 0.1%
formic acid (flow 5 ml/min). After 0.75 min, the switching valve was
activated, and the analytes were eluted in the backflush mode from the
extraction column onto the 50 × 4.6 mm C8, 3.5-µm analytical
column (Zorbax; Agilent Technologies, Palo Alto, CA). The mobile phase
was methanol and 0.1% formic acid supplemented with 1 µmol/l sodium
formate. The gradient was run time 0 min, 35% methanol; 7 min, 75%
methanol; and 9 min, 90% methanol (flow rate, 0.5 ml/min). Both
columns were kept at 65°C. Single ions [M + Na]+ were recorded. The mass spectrometer
(G1946A mass selective detector; Hewlett-Packard) was focused on
m/z = 1224 (cyclosporine),
m/z = 1238 (internal standard cyclosporin D)
(Christians et al., 2000; Serkova et al., 2000).
Statistical Analysis. Values are expressed as mean ± standard deviation, if not otherwise designated. In the MRS study, concentrations between the controls and cyclosporine-treated animals were compared using unpaired Student's t test. The effects of cyclosporine on infarct size were compared between controls and cyclosporine dose groups using analysis of variance in combination with Duncan grouping as a post hoc test. The relationship among doses, metabolite concentrations, and blood and tissue concentrations as well as cyclosporine concentrations and infarction size were assessed using correlation analysis. The SPSS software package (version 10.07; SPSS Inc., Chicago IL) was used to calculate distribution statistics and for all statistical analyses. A P value of <0.05 was considered significant.
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Results |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Effect of Cyclosporine on Myocardial Energy Metabolism.
ATP,
ADP, phosphocreatine, NAD+/NADH, and
water-soluble phospholipids were quantified based on
31P MR spectra (Fig.
1). The following cell metabolites could
be detected and were quantified using 1H MRS of
heart PCA extracts: 1) glycolysis intermediates lactate and alanine; 2)
Krebs' cycle products glutamate, glutamine, and succinate; 3)
high-energy phosphates creatine/phosphocreatine; 4) osmolytes taurine;
and 5) glutathione. Three days of cyclosporine oral treatment
significantly reduced cardiac high-energy phosphates as indicated by a
dose-dependent decrease of ATP and phosphocreatine concentrations as
well as by reduction of the [ATP/ADP] and
[phosphocreatine/creatine] ratios surrogate markers for (Table
1). The concentration of NAD+/NADH, surrogate markers for oxidative
phosphorylation, was decreased after treatment (Table 1) and correlated
positively (r = 0.89, P < 0.002) with
the ATP levels. Furthermore, cyclosporine significantly reduced Krebs'
cycle intermediates by as much as 35% (glutamate at a dose of 25 mg/kg/day) (Table 1). A positive correlation with the ATP
concentrations was found for both glutamate (r = 0.95, P < 0.001) and glutamine (r = 0.84, P < 0.002). In parallel, the concentrations of
lactate, the end product of anaerobic glycolysis, were significantly
increased in all treatment groups (Table 1) and inversely correlated
with ATP concentrations (r = 0.93, P < 0.001). The increase in lactate production was associated with a
decrease in glucose concentrations that correlated with the reduction
in high-energy phosphate concentrations (ATP: r = 0.92, P < 0.001).
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Effect of Cyclosporine on Infarct Size in Rats.
Cyclosporine
at doses of 10 and 15 mg/kg/day significantly reduced the size of
infarct relative to the area at risk (P < 0.03). At a
dose of 15 mg/kg, the percentage of left ventricular infarct was 4-fold
smaller than in the control rats (15 mg/kg/day, 7.3 ± 6.7%
versus control, 29.4 ± 5.7%). Cyclosporine dose of 25 mg/kg/day resulted in slightly less protection than the dose of 15 mg/kg/day (area of infarct/area at risk at 25 mg/kg/day, 17.0 ± 14.6%
versus 15 mg/kg/day, 13.9 ± 12.9%; Fig.
2). The difference between the two
doses, however, was not statistically significant. The relative sizes of the areas at risk/area of the left ventricle were similar in the different dose groups as evaluated by analysis of variance (Fig.
2). Concentrations of the high-energy phosphates ATP and NAD+/NADH in the control group significantly
correlated with the ratios [area of infarction/area at risk] and
[area of infarction/area of the left ventricle] (r = 0.97, P < 0.001 and r = 0.82, P < 0.01, respectively).
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Cyclosporine Blood and Cardiac Tissue Concentrations.
Cyclosporine doses were significantly correlated with cyclosporine
concentrations in blood (r = 0.81, P < 0.001), in normal myocardial tissue (r = 0.86, P < 0.001), and in the infarcted tissue
(r = 0.87, P < 0.001) but not in the
area of risk (Fig. 3). A significant
inverse correlation was evident between the cyclosporine dose (blood
concentration) and the percentage of area of infarct/area of risk as
well as the percentage of area of infarct/area of the left ventricle
with r = 0.81, P < 0.01 and
r = 0.86, P < 0.01, respectively. If
the 25 mg/kg/day was excluded from the analysis, the correlation
coefficients improved to 0.86 and 0.91, respectively. In addition,
there was a significant negative correlation between the
cyclosporine dose and ATP (r = 0.89,
P < 0.01), NAD+/NADH
(r = 0.94, P < 0.001), glutamate
concentrations (r = 0.83, P < 0.02),
and a significant positive correlation with the lactate concentrations
(r = 0.87, P < 0.002).
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Discussion |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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The main result of the present study is that cyclosporine inhibits
cardiac high-energy phosphate and Krebs' cycle metabolism in a
dose-dependent fashion. Comparable data have not been previously reported in the literature. Our MRS data indicate that cyclosporine inhibits the Krebs' cycle (decreased glutamate/glutamine
concentrations) and mitochondrial oxidative phosphorylation (decreased
concentrations of NAD+), resulting in a
significant cellular reduction in ATP and phosphocreatine with a
concomitant increase of ADP concentration. The inhibition of
mitochondrial energy production caused lactate accumulation followed by
elevated fatty acid oxidation at the high cyclosporine doses. The
increased lactate concentrations in the cyclosporine-treated rats can
be explained by compensatory stimulation of anaerobic ATP synthesis via
glycolysis (Schlant, 1978). The decrease of fatty acids at the highest
treatment dose (25 mg/kg/day cyclosporine) can be attributed to the
increased stimulation of fatty acid oxidation, which is another
additional alternative pathway for energy production (Schlant, 1978),
when oxidative mitochondrial pathway remains largely inhibited by
cyclosporine. This may explain the increased lipid peroxidation in the
25 mg/kg/day cyclosporine-treated group. Malondialdehyde, one of the
main products of lipid peroxidation, indirectly measured in our TBA
test, is generated during hydrolysis by oxidation of PUFA (Draper and
Hadley, 1990; Suttnar et al., 1997). PUFA concentrations, as well as
the total fatty acid pool, were decreased in 25 mg/kg/day treated rats
and correlated with the increased LPO. The biochemical depression of
mitochondrial glucose and high-energy phosphate metabolism found in our
study are very similar to those induced by cyclosporine in the brain (Serkova et al., 2001, 2002). The ability of cyclosporine to decrease the energy state by inhibiting mitochondrial metabolic pathways has
also been reported for the kidney (Henke et al., 1992) and, more
recently, it has been shown that cyclosporine produces hypoxia-like conditions in the normoxic liver as well (Zhong et al., 2001). The
mechanism of cardiac energy depression is not clear, and the present
study design does not allow one to answer this specific question.
However, our MRS results suggest that the effects of cyclosporine on
myocardial cell metabolism mimic to a certain extent the effects of
hypoxia. Hypoxic-like conditions, which result in the depletion of
mitochondrial energy homeostasis, can produce the protective effect on
myocardium against prolonged ischemia/reperfusion damages (Murry et
al., 1986; Garnier et al., 1996). It can be speculated that by inducing
metabolic changes similar to hypoxia, cyclosporine may also have
ischemic preconditioning effects. Besides direct depression of
mitochondrial respiration, another possible mechanism, such as
induction of heat shock protein expression as shown for the kidney
(Yang et al., 2001), may be involved in cyclosporine-induced
pharmacological preconditioning. However, the potential contribution
and the exact mechanism of cyclosporine-induced preconditioning will
require further assessment.
This study showed the salutary effect of cyclosporine on infarct size
in rats subjected to 30 min of coronary occlusion. Pretreatment with
cyclosporine for 4 days was based on the rationale that protective and/or adaptive mechanisms, such as pharmacological preconditioning, induced by cyclosporine may depend on changes of gene expression that
may take hours to days for full effect. We found that within 24 h
of 30 min of coronary artery occlusion, cyclosporine pretreatment produced a dose-dependent reduction in infarct size relative to the
area at risk and to the area of the left ventricle. Our evaluation of
different doses suggested maximum protective effect at doses between 10 and 15 mg/kg/day, with a fall-off at higher doses (25 mg/kg). This
finding is in good agreement with those of Griffiths and Halestrap
(1993) who observed that in isolated perfused hearts the
cardioprotective effect was dose-dependent with an apparent reversal of
the protective effect at higher doses. Furthermore, the ratio [area of
infarct/area at risk] in the occlusion group strongly correlated with
the decrease of cellular ATP and NAD+
concentrations in control rats. Doses of 10 and 15 mg/kg/day cyclosporine produced inhibition of mitochondrial energy production prior to occlusion, resulting in a decrease in infarct size after 24 h of reperfusion. At 25 mg/kg/day cyclosporine, the positive effect of cyclosporine appears to be antagonized, possibly due to an
increased lipid peroxidation.
Other effects of cyclosporine, such as inhibition of the immune
response following ischemia/perfusion injury, have also been described,
which may contribute to the beneficial effect of cyclosporine on
ischemia/reperfusion injury (Squadrito et al., 1999). Griffiths and Halestrap (1993) found that cyclosporine keeps the mitochondrial nonspecific pores closed during reperfusion. This effect was not dependent on calcineurin inhibition but most likely due to inhibition of cyclophilin D, since a nonimmunosuppressive cyclosporine derivative was equally as effective as cyclosporine. Weinbrenner et al. (1998) found evidence that cyclosporine protects the ischemic rabbit heart by
inhibiting the calcium-calmodulin-dependent protein phosphate 2B,
calcineurin. Massoudy et al. (1997) reported that cyclosporine acts as
a cardioprotective agent by an endothelin-dependent mechanism. None of
these studies pretreated animals with cyclosporine or were based on
isolated hearts; in the only in vivo study reported (Squadrito et al.,
1999), cyclosporine was administered intravenously 15 min after
coronary occlusion. We also measured cyclosporine concentrations in the
remote nonischemic myocardium, the area at risk, and the infarcted area
by using a highly specific and sensitive, validated HPLC/MS assay.
Since cyclosporine oral bioavailability is known to be erratic and
variable (Oellerich et al., 1995), we also measured cyclosporine blood
concentrations. Our study suggested a good correlation between the oral
cyclosporine dose and cardiac tissue concentrations as well as a good
correlation between blood and cardiac tissue concentrations. The
cyclosporine doses and blood concentrations that produced significant
reduction of the area of infarction are comparable with those obtained
in/desired in patients after heart transplantation (Oellerich et al.,
1995). In conclusion, cyclosporine, in a dose-dependent fashion,
induced depression of the cardiac energy metabolism before occlusion
and decreased infarct size in a rat coronary occlusion model. The depression of cardiac energy metabolism induced by cyclosporine correlated with the reduction in infarct size and suggests that cyclosporine pretreatment produces an energetic milieu similar to that
achieved by ischemic preconditioning. Further studies are needed to
test the effect of cyclosporine on cardiac function and the severity of
myocardial injury.
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Acknowledgments |
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We thank Karen Baner (Department of Biopharmaceutical Sciences, School of Pharmacy, University of California, San Francisco) for valuable assistance with the animal experiments, and Sven Gottschalk and Carsten Hainz (Department Chemistry/Biology, University of Bremen, Germany) for help in performing the lipid peroxidation analysis.
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Footnotes |
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Accepted for publication May 9, 2002.
Received for publication April 1, 2002.
This study was supported in part by Grants Se 985/1-1 (to N.S.) and Ch 95/6-2 (to U.C.) from the Deutsche Forschungsgemeinschaft (Germany).
DOI: 10.1124/jpet.102.036848
Address correspondence to: Dr. Natalie Serkova, University of Colorado Health Sciences Center, Department of Anesthesiology, 4200 East Ninth Avenue, Room 2122, Campus Box B-113, Denver, Colorado 80262. E-mail: natalie.serkova{at}uchsc.edu
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Abbreviations |
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MRS, magnetic resonance spectroscopy; PCA, perchloric acid; NMR, nuclear magnetic resonance; LPO, lipid peroxidation; TBA, thiobarbituric acid; LC, liquid chromatography; HPLC, high-pressure LC; MS, mass spectroscopy; PUFA, polyunsaturated fatty acids; TAG, triacylglycerides.
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References |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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evidence for a nitric oxide-dependent mechanism mediated by endothelin.
J Mol Cell Cardiol
29:
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