(1): 7-17, 2010 AGAINST THE HEPATIC INJURY IN RATS
台灣獸醫誌 Taiwan Vet J 36ALPROSTADIL
7
Effect of Prostaglandin E1 Analogue, Alprostadil, against the
Hepatic Ischemia-Reperfusion Injury in Rats
1,2
Cheng-Chu HSIEH, *3,4 Jen-Hwey CHIU, *1 Ying-Ling WU
1
2
3
4
（Received: November 27, 2008. Accepted: January 21, 2010）
[Hsieh CC,
* Chiu JH, * Wu YL. Effect of Prostaglandin E1 Analogue, Alprostadil, against the Hepatic Ischemia-Reperfusion Injury in Rats. Taiwan Vet J 36 (1): 7-17, 2010. * Corresponding author, Wu YL TEL: 886-2-3366-1302,
FAX: 886-2-2366-1475, E-mail: wuyl@ntu.edu.tw; Chiu JH TEL: 886-2-2826-7178, FAX: 886-2-2822-5044,
E-mail: chiuih@mailsrv.ym.edu.tw]
INTRODUCTION
Hepatic I/R injury occurs during circulating shock, disseminated intravascular coagulation, liver
transplantation and surgery, cardiac failure and arrest,
alcohol toxicity and several other pathological condi-
tions. Different mechanisms of injury contribute to the
overall pathophysiology of hepatic I/R injury. Because
the liver is a highly oxygen-utilizing organ, impairment of blood flow rapidly causes hepatic hypoxia,
which progresses to absolute anoxia, especially in
pericentral regions of the liver lobes [12].
8
Cheng-Chu HSIEH et al
Oxygen-derived free radicals have been widely
known in I/R injury in many organs including the heart
and the liver. Among the systemic consequences of reperfusion, lipid peroxidation is probably the most
damaging effect resulting in structural and functional
derangement and death of cells eventually [29].
Production of reactive oxygen species, including
superoxide, hydrogen peroxide and hydroxyl radicals
has long been implicated in reperfusion injury, but
oxygen independent factors are important as well,
such as tissue pH changes during I/R [17]. Inflammatory responses and microcirculatory problems further
aggravate injury after reperfusion. I/R activates
Kupffer cells, the resident macrophages of the liver.
Functional inactivation of Kupffer cells attenuates injury during early and late reperfusion [19]. Kupffer
cells after reperfusion generates reactive oxygen species, proinflammatory cytokines, chemokines, and
other mediators that contribute to postischemic tissue
injury, systemic inflammatory response syndrome and
multiorgan failure, thereby potentially leading to a severe ischemic insult to the liver. Together with activated complement factors, these inflammatory mediators activate and recruit neutrophils into the postischemic liver, which generates even more reactive oxygen and releases additional proteases and other degradative enzymes [21]. In addition to the inflammatory response, vasoconstriction of sinusoids induced
by endothelin-1 promotes heterogeneous closure of
many microvessels, which prolongs ischemia in certain areas of the liver even after reperfusion [29].
PGE1, a naturally occurring prostaglandin, is
originally introduced as a therapeutic agent because of
its potent direct vasodilator actions. Several experiments indicate a beneficial effect of intravenously administered with PGE1 in patients with chronic vascular disease [1]. It has been hypothesized that these clinical effects of PGE1 can be attributed to its direct potential vasodilatory effect to lead an increased perfusion in local tissue.
Alprostadil is the synthetic form of PGE1, which
is a naturally occurring lipid compound with the molecular formula C20H34O5, one of the family of occurring acidic lipid with various pharmacological effects.
Alprostadil is a prostaglandin analogue that produces
a strong relaxant effect on smooth muscles of peri-
pheral blood vessels. It has both peripheral vasodilator
and platelet aggregation inhibitor activities exhibited
through raising cAMP concentrations via adenylate
cyclase activation.Alprostadil interacts with specific
G-protein coupled receptors and raise cAMP and also
elicits an increase in the level of plasma adenosine.
Adenosine is an endogenous by-product of purine metabolism. Extracellular increase of adenosine causes
vasodilation, reduction of leukocyte activity, endothelial protection, inhibition of platelet aggregation,
amelioration of the rheological properties of blood
with an increase of oxygen delivery to tissues [15]. Alprostadil is also widely used for the treatment of vascular diseases associated with impaired function of endothelial cells. Alprostadil has been demonstrated to
exert direct and indirect vascular actions such as vasodilation and enhancement of blood viscosity [1]. In
addition, alprostadil has fibrinolytic, antithrombotic,
and platelet anti-aggregatory properties. Although alprostadil has been used in patients with critical limb
ischemia for several years, its effect on the ocular vasculature has not been adequately studied and only a
few anecdotal reports are available [25].
In the present study, the protection of PGE1 against hepatic I/R-induced tissue damage was examined by measurement of biochemical parameters, such
as the level of malondialdehyde (MDA) in the liver, an
end product of lipid peroxidation; the level of catalase
(CAT), glutathione (GSH) and superoxide dismutase
(SOD), key antioxidants; myeloperoxidase (MPO) activity, an indirect index of neutrophil infiltration; the
level of nitric oxide (NO), an index of total nitrate/nitrite.
MATERIAL AND METHODS
Animals Male Sprague-Dawley rats, weighing
250-300 g, were obtained from the animal center of
the National Science Council, Taiwan, R.O.C. The rats
were fed on standard diets, allowed free access to water and treated according to the “Guide for the Care and
Use of Laboratory Animals” (National Academy Press, 1996). The studies were approved by the committee of experimental animals of National Yang-Ming
University.
ALPROSTADIL AGAINST THE HEPATIC INJURY IN RATS
Experimental groups Eighteen male SpragueDawley rats were randomly divided into three groups
including the control group, I/R group and I/R + PGE1
group (n = 6). The rats in the control group did not
undergo any treatment. The rats in I/R group were subjected to 60 min of hepatic ischemia followed by 60
min of reperfusion period. The rats in I/R + PGE1 group were injected continuously with PGE1 (0.05 g/kg)
30 min prior to ischemia and alone with reperfusion
period.
Animal model and parameters for I/R injury
of the liver I/R was performed as previously described [4]. In brief, male Sprague-Dawley rats were
anesthetized with urethrane (1.25 g/kg, i.p.), and the
trachea was cannulated with a ventilator for artificial
respiration. Polyethylene (PE-50) catheters were cannulated into the femoral artery to monitor the blood
pressure with a polygraph (Gould, RS 2400). The liver
was exposed through an upper midline incision, and
two pieces of fine silk were looped along the right and
left branches of the portal vein, hepatic artery, and bile
duct. The silk was then fashioned into a snare with a
piece of PE-90 that allowed the occlusion of blood
supply to either the median/left lobes (left branch). For
I/R injury study, ischemia of left/median lobes were
maintained for 60 min followed by reperfusion of left/
median lobes with immediate occlusion of the right
lobe vasculature for another 60 min. After one hour for
completion of the reperfusion procedure, the initial
ischemic-reperfused left/median lobes were resected
and tested for MPO, MDA, GSH, CAT, SOD and NO
determination. Blood for ALT/AST measurement was
collected immediately after the femoral catheterization and the completeness of reperfusion procedure.
Biochemical analysis
Myeloperoxidase (MPO) assay MPO activity
was measured in the liver tissue by a procedure similar
to that documented by Hillegas et al. The liver samples
were homogenized in 50 mM potassium phosphate
buffer (PB, pH 6.0) followed by centrifuged at 41,400
×g for 10 min and the pellets were suspended in 50
mM PB containing 0.5% hexadecyltrimethylammonium bromide (HETAB). After three cycles of freezing and thawing with sonication between cycles, the
9
samples were centrifuged at 41,400 ×g for 10 min.
Aliquots (0.3 mL) were added to 2.3 mL of reaction
mixture containing 50 mM PB, o-dianisidine, and 20
mM H2O2 solution. One unit of enzyme activity is defined as the amount of MPO present that causes a
change in absorbance measured at 460 nm for 3 min.
MPO activity was expressed as U/g tissue.
Malondialdehyde (MDA) assay The samples
from the liver tissue were homogenized with ice-cold
KCl (150 mM) for determination of MDA levels. The
MDA levels were assayed for products of lipid peroxidation. Results were expressed as nmoL MDA/g tissue.
Glutathione (GSH) assay Hepatic levels of glutathione were determined by using a commercialized
GSH assay kit (Cayman Chemical Co., Ann Arbor,
MI, USA). Cayman’s GSH assay kit utilizes a carefully optimized enzymatic recycling method, using glutathione reductase for the quantification of GSH. Tissue was homogenized in 5-10 mL of cold buffer (i.e.,
50 mM MES or phosphate, pH 6-7, containing 1 mM
EDTA) per gram of tissue and centrifuged at 10,000
×g for 15 min at 4℃ followed by deproteinization
with metaphosphoric acid. After adding triethanolamine solution and Assay Cocktail (a mixture of 11.25
mL MES buffer, 0.45 mL reconstituted cofactor mixture, 2.1 mL reconstituted enzyme mixture, 2.3 mL
water, and 0.45 mL reconstituted DTNB), total GSH
in the deproteinated sample was measured at 405 or
414 nm in a spectrophotometer. The concentration of
GSH in the samples were determined by the End Point
Method and expressed as microns.
Catalase (CAT) assay Hepatic CAT activity was
determined by using a commercialized chemical CAT
assay kit (Cayman Chemical Co.). The kit utilized the
peroxidatic function of CAT for determination of enzyme activity. Tissue was homogenized in 5-10 mL of
cold buffer (50 mM potassium phosphate, pH 7.0, containing 1 mM EDTA) per gram of tissue and centrifuged at 10,000 ×g for 15 min at 4℃. The sample was
added sequentially with hydrogen peroxide, potassium hydroxide, Purpald ® and potassium periodate,
and then the absorbance was read at 540 nm. The ac-
10
Cheng-Chu HSIEH et al
RESULTS
tivity of CAT was recorded as nmoL/min/mL.
Superoxide dismutase (SOD) assay Hepatic
SOD activity was determined by using a commercialized chemical SOD assay kit (Cayman Chemical Co.).
The kit utilizes a tetrazolium salt for detection of
superoxide radicals generated by xanthine oxidase and
hypoxanthine. Tissue was homogenized in 5-10 mL of
cold buffer (20 mM HEPES buffer, pH 7.2, containing
1 mM EDTA, 210 mM mannitol and 70 mM sucrose)
per gram of tissue and centrifuged at 1,500 ×g for 5
min at 4℃. The reaction was initiated by adding
xanthine oxidase and incubated for 20 min at room
temperature, and read the absorbance at 450 nm. One
unit of SOD activity was defined as the amount of enzyme needed to inhibit 50% dismutation of the superoxide radical.
Nitric oxide (NO) assays Hepatic NO was determined by using a commercialized chemical Nitrate/
Nitrite Colorimetric Assay Kit (Cayman Chemical
Co.). The kit provided an accurate and convenient
method for measurement of total nitrate/nitrite concentration in a simple two-step process. The first step
was the conversion of nitrate to nitrite by nitrate reductase. The second step was the addition of the Griess Reagents which convert nitrite into a deep purple
azo compound. Photometric measurement of the absorbance, which is increased by azo chromophore production, accurately determines NO concentration.
The level of ALT and AST was increased significantly in I/R group compared to the control group. Although these values were decreased significantly in
the PGE1 treatment, preconditioning of PGE1 with the
combination of I/R led the level of ALT and AST back
to control level (Table 1).
Myeloperoxidase (MPO) levels In the I/R group, MPO levels (32.5 ± 0.8 U/g) were found to be increased significantly when compared to the control
group (15.4 ± 0.6 U/g). Compared to the I/R group, it
was not found to be significantly decreased in the I/R
+ PGE1 group (30.6 ± 1.8 U/g) (Fig. 1)
Malondialdehyde (MDA) levels The liver
MDA was found to be significantly increased in the I/
R group (1.47 ± 0.15 M) than in the control group
(0.73 ± 0.04 M). In the I/R + PGE1 group (1.29 ±
0.19 M) MDA levels were not found to be decreased
significantly compared to the I/R group (Fig. 2).
Glutathione (GSH) levels The levels of GSH in
the liver tissue showed a tendency to decrease after I/
R, which was statistically different from that of the
control group (303.2 ± 28.3 M). In the I/R + PGE1
group (155.1 ± 11.0 M) GSH levels were not found
to be increased significantly compared to the I/R group (154.6 ± 11.3 M) (Fig. 3).
Histological analysis After decapitation of rats,
Catalase (CAT) levels The levels of CAT in the
small pieces of liver tissue were placed in 10% (vol/
vol) formaline solution and processed routinely by
embedding in paraffin. Tissue sections (4-5 m) were
stained with Hematoxylin & Eosin (H & E) and examined under a light microscope.
liver tissue showed a tendency to decrease after I/R,
which was statistically different from that of the control group (260.0 ± 29.2 M). In the I/R + PGE1 group
(169.0 ± 26.6 M) CAT levels were not found to be increased significantly compared to the I/R group (170.0
Statistical analysis The data in each experimental
group were analyzed and expressed as means ± SEM.
Concentrations of MPO, MDA, GSH, CAT, SOD, NO,
ALT, and AST in different groups were determined by
using the Wilcoxon signed rank test for paired data
and Mann-Whitney U test for comparison between
different groups. P value less than 0.05 was indicated
statistical significance.
Plasma ALT and AST activities (n=6).
ALT (U/L)
AST (U/L)
Control group
57.5 ± 5.6*
104 ± 16*
I/R group
847 ± 120
1402 ± 255
I/R + PGE1 group
483 ± 42*
*p < 0.05, compared with I/R group.
834 ± 139*
ALPROSTADIL AGAINST THE HEPATIC INJURY IN RATS
11
400
40
375
35
350
*
300
30
275
25
20
*
15
Glutathione ( M)
Myeloperoxidase (U/g)
325
10
250
225
200
175
150
125
100
75
5
50
25
0
I/R
PGE1
0
I/R
PGE1
t of I/R and its treatment with PGE1 on MPO levels of liver tissue. * < 0.05, compared to I/R group (n=6).
Effect of I/R and its treatment with PGE1 on GSH
levels of liver tissue. * < 0.05, compared to I/R group
(n=6).
2.5
350
325
300
*
275
250
225
1.5
1.0
*
Catalase ( M)
Malondialdehyde ( M)
2.0
200
175
150
125
100
0.5
75
50
25
0.0
I/R
PGE1
Effect of I/R and its treatment with PGE1 on MDA
levels of liver tissue. * < 0.05, compared to I/R group
(n=6).
0
I/R
PGE1
Effect of I/R and its treatment with PGE1 on CAT
levels of liver tissue. * < 0.05, compared to I/R group
(n=6).
12
Cheng-Chu HSIEH et al
± 19.3 M) (Fig. 4).
Superoxide dismutase (SOD) levels The levels
of SOD in the liver tissue showed a tendency to decrease after I/R, which was statistically different from
that of the control group (59.9 ± 2.9 M). PGE1 treatments significantly elevated the SOD levels (46.2 ±
4.2 M) compared to the I/R group (36.9 ± 2.7 M)
(Fig. 5).
Nitric oxide (NO) levels The levels of NO in the
liver tissue showed a tendency to decrease after I/R,
which was statistically different from that of the control group (17.6 ± 2.2 M). PGE1 treatments significantly elevated the NO levels (20.6 ± 1.0 M) compared to the I/R group (28.9 ± 3.4 M) (Fig. 6).
Histological results In the control group, the normal liver parenchyma cells appear as regular morphology of both hepatocytes and sinusoids around the central vein. In the I/R group, hepatocytes are prominen-
tly swollen with marked vacuolization. Congestion is
noticed in enlarged sinusoids. The liver parenchyma
cells showed irregular morphology in both hepatocytes and sinusoids around the central vein. In the I/R
+ PGE1 group, hepatocytes and sinusoids represent
normal morphology reflecting a well preserved liver
parenchyma cells.
DISCUSSION
The present study demonstrates that PGE1 improves the function of liver, significantly decreases I/
R-induced elevations of NO, and maintains the level
of SOD. Histological findings also support the protective role of PGE1.
Hepatic I/R injury occur in many clinical scenarios including transplantation, trauma and hepatectomy. The main pathophysiological events during this
injury comprise the depletion of ATP, Kupffer cell activation with subsequent formation of reactive oxygen
species (ROS), formation of proinflammatory media-
80
40
70
35
60
50
30
*
40
30
Nitric Oxide ( M)
Superoxide dismutase ( M)
*
25
*
20
15
20
10
10
5
0
I/R
PGE1
0
I/R
PGE1
Effect of I/R and its treatment with PGE1 on SOD
levels of liver tissue. * < 0.05, compared to I/R group
(n=6).
*
Effect of I/R and its treatment with PGE1 on NO
levels of liver tissue. * < 0.05, compared to I/R group
(n=6)
ALPROSTADIL AGAINST THE HEPATIC INJURY IN RATS
Control group
I/R group
I/R+PGE1 group
Histological results. In the control group, the normal liver parenchyma cells showed regular morphology in
both hepatocytes and sinusoids around the central vein.
In I/R group, hepatocytes are prominently swollen with
marked vacuolization ( ). Congestion ( ) is noticed in
enlarged sinusoids. The liver parenchyma cells showed
irregular morphology in both hepatocytes and sinusoids
around the central vein. In the I/R + PGE1 group, hepatocytes and sinusoids represent normal morphology reflecting a well preserved liver parenchyma cell. (H & E, 400
X)
tors, and recruitment and activation of macrophages,
neutrophils and lymphocytes. Depending on the severity of I/R injury, cell damage leads to necrotic or apoptotic liver cell death and results in organ dysfunction
or even nonfunction. Oxygen-derived free radicals
have been widely known in I/R injury in many organs
including the heart and liver. The aim of these treatments was to restore the blood supply to the ischemic
liver. Unfortunately, restoration of blood flow to
ischemic tissues can lead to further damage. The para-
13
dox leads uncertain effectiveness of these strategies. I/
R injury is a complex pathophysiology with a number
of contributing factors. Therefore, it is difficult to
achieve effective treatment or protection by targeting
individual mediator or mechanism. In contrast, the
most promising protective strategy against I/R injury
explored during the last few years is preconditioning.
Preconditioned fasting, ischemia, pharmaceutical
molecules, hyperosmolar solutions, and local somatothermal stimulation (LSTS) [5,28] have been studied
and appeared to increase the resistance of cells to
ischemia and reperfusion events.
With regard to the animal model used in this study, it is well-known that simultaneous occlusion of the
right lobe vasculature with reperfusion of left/median
lobes while making sure that the ischemic lobes have
been well reperfusion is suggested to be a good model
for studies on hepatic I/R injury [18]. In addition, the
determination of the time periods of I/R was important. Too-short (< 20 min) or too-long (> 90 min)
ischemia time might result in little or irreversible
structural and functional changes respectively. Sinusoidal perfusion failure was found to be aggravated
when the ischemic time period was prolonged to 60
min [14]. Using 60 min of left/median lobar ischemia
followed by 60 min of reperfusion as a model, our results showed distinct functional alterations (Table 1),
and this model provided a reproducible system for studying the protective effect of PGE1 on hepatocytes in
I/R injury.
There is a lot of evidence indicating that many
physiological and pathophysiological phenomena
such as ageing, carcinogenesis, drug toxicity, inflammation, viral infections, myocardial infarction, neurodegenerative disease and other disease may be developed through the action of reactive oxygen species.
Some strategies have been developed to enhance antioxidant capacity including scavenging of reactive
oxygen species and increasing of intracellular antioxidative defense.
Prostaglandins are released mainly by activated
Kupffer cells during the reperfusion phase [8]. Animal
studies proved that prostaglandins are effective in the
treatment of ischemic liver injury owing to their ability to increase liver perfusion, inhibit platelet aggregation and also directly exhibit cytoprotection in a model
14
Cheng-Chu HSIEH et al
of isolated perfused feline liver [2]. The protective action of PGE1 may be related to their ability to reduce
both the release of proteases and the generation of
oxygen free radicals from activated leukocytes. In addition, because of the synergistic role of platelets and
leukocytes and the interaction of these cells with the
liver sinusoidal endothelial cells (LSECs) during the
reperfusion phase [24], it is conceivable that the effects of PGE1 on leukocyte adherence may account
for their favorable action. Greig et al. [9] found that
the function of liver could be restored by treatment
with a PGE1 analog after reperfusion and progression
to primary dysfunction. The use of pharmacological
dosage of natural prostaglandins in clinical settings is
limited because of drug-related side effects [27]. Synthetic prostaglandin analogs were associated with milder side effects and a longer half-life. Several of these
analogs improved animal survival and prevented parenchymal injury after prolonged periods of warm
hepatic inflow occlusion.
Evidence has been claimed recently that reactive
oxygen metabolites play a basic role in the hepatoxicity of various xenobiotics and medications. Oxidative
stress playing a crucial role in the liver damage of I/R
injury and the reduction of this negative effect by antioxidant therapies were shown in experimental studies
published recently [7].
SOD is an important protective system, which accelerates the dismutation of superoxide anion radicals
to hydrogen peroxide and acts as a primary defense to
prevent further generation of free radicals. Results of
the studies examining the status of the antioxidant enzyme SOD in experimental colitis are controversial.
Kuralay et al. showed that tissue SOD levels were elevated in response to oxidative stress in experimental
colitis model, and were decreased by antioxidant agents [16].
Moreover, SOD catalyses the dismutation of the
superoxide anion (O2) into H2O2, which can be transformed into H2O and O2 by CAT. It has been shown
that SOD activity and content decreased after I/R injury presumably via inactivation/degradation of mature and active SOD within mitochondria [23].Manson et al. first demonstrated that the administration of
SOD, an endogenous scavenger of reactive oxygen
species, enhanced the survival of skin flap after arter-
ial and venous occlusion [20]. Cardioplegic solutions
containing SOD enhanced postoperative cardiac contractile function after hypothermic global ischemia in
dogs [26]. However, the administration of free radical
scavengers after the onset of reperfusion was ineffective. Therefore, the generation of oxygen radicals is
likely to be a transient early event.
Our results showed that SOD in hepatic I/R injury alone group is lower than that in control group.
Because the I/R injury may produce a large number of
oxygen free radicals, SOD is used too much, which results in decrease of anti-oxidant ability. PGE1 is likely
to suppress the release of oxygen free radicals and inflammation mediators, which has an effect on the amount of SOD. This also reduces free radicals in the
body and consumption of SOD. After treatment of
PGE1, the amount of SOD will increase.
Oxidative stress is also commonly associated
with relatively high levels of reactive nitrosative species and reactive oxygen and nitrogen species [10].
NO is synthesized by a family of enzymes termed
NOS. Two of them, the so-called endothelial (eNOS)
and neuronal (nNOS) isoforms, are expressed constitutively and generate NO for cell signaling purposes.
The inducible isoform releases NO in large amounts
during inflammatory or immunologic reactions and involved in host tissue damage responses. The reaction
of superoxide anion and NO produces peroxynitrite
(ONOO ), which can readily modify proteins and
other molecules [11]. In addition to genetic alterations,
ROS may cause epigenetic alterations that strongly affect gene expression without changing the DNA base
sequence. (The mechanisms that have been proposed
to explain the I/R renal injury include anoxia followed
by releasing of oxygen-derived free radicals during reperfusion, leading to endothelial cell dysfunction with
decreased NO release and inhibiting leukocyte-endothelial adhesion and activation [3].) Superoxide anion,
one of these free radicals, can interact with NO to generate peroxynitrite, a potent and cytotoxic oxidant that
could cause renal vasoconstriction and medullary
ischemia, thus contributing to the persistent reduction
in medullary perfusion associated with acute renal
failure [6].
NO, an endothelial-dependent relaxation factor,
has many physiological functions and plays an import-
ALPROSTADIL AGAINST THE HEPATIC INJURY IN RATS
ant role in modulating tissue injury including proapoptosis and antiapoptosis properties. These effects of NO
as a double-edged sword have been well studied. The
different roles of NO in either cytoprotection or cytotoxicity depends on the quantity of NO and isoforms
of NO synthase expressed in the relevant tissues. NO
produced at low levels is associated with cellular
eNOS expression [13] and inhibiting cell apoptosis
and the mechanisms was involved sustain Bcl-2 levels
or posttranslational modification of interleukin-1 converting enzyme (ICE)/cysteine protease protein
(CPP)-32-like proteases.In contrast, high amount of
NO production is related to cellular iNOS expression
and lead direct DNA damage or cell apoptosis by activation of apoptotic signaling pathways [22]. Thus far,
evidence that NO protects from I/R injury has been
obtained from in vivo models. The protective effect of
NO was considered to be mediated indirectly by
modulating of blood circulation, attenuating leukocyte
adhesion and activation, inhibiting of platelet aggregation, scavenging superoxides and maintaining vascular endothelial integrity. However, the direct effect of
NO on endothelial cells during I/R injury remains
poorly understood. According to Yang’s study [30],
there was a direct toxic role of NO on LSECs during
hypoxia reoxygenation. First, the production and expression of eNOS and iNOS were increased in LSECs
during hypoxia reoxygenation. Second, a NO inhibitor, N- -nitro-l-arginine (L-NAM), protected LSECs
against apoptosis, while a NO activator, S-nitroso-Nacetylpenicillamine (SNAP), increased LSEC apoptosis during hypoxia reoxygenation. PGE1 inhibited
NO production and NO synthase expression in LSECs
during hypoxia reoxygenation. It indicates that the
protective role of PGE1 is related to the downregulation of NO production. These results provided an evidence for a direct toxic role of NO in hepatic I/R injury.
In summary, preconditioned PGE1 had a beneficial effect on protecting the rat liver against I/R injury.
PGE1 is an easily applicable alternative and will bring
into perspective the clinical prevention of ischemic
liver disease or liver transplantation.
15
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ALPROSTADIL AGAINST THE HEPATIC INJURY IN RATS
17
前列腺素 E1 類似物 (Alprostadil) 對於大白鼠肝臟缺血再灌流損傷
保護效果之探討
1,2
謝政橘
*3,4 邱仁輝
*1 吳應寧
國立臺灣大學獸醫專業學院獸醫學系 (所) 臺北市
行政院農業委員會家畜衛生試驗所製劑研究組 淡水鎮臺北縣
3
臺北榮民總醫院外科部一般外科 臺北市
4
國立陽明大學醫學院傳統醫藥學研究所 臺北市
1
2
（收稿日期：97 年 11 月 27 日。接受日期：99 年 1 月 21 日）
摘要
實驗的目的在探討前列腺素 E1 類似物 (alprostadil) 在大白鼠肝臟缺血再灌流時的影響。使用 Sprague-Dawley
品系雄性的大白鼠為實驗動物，以外科手術造成肝臟缺血 60 分鐘後，緊接著再灌流 60 分鐘。在大白鼠肝臟缺血前
30 分鐘先給予前列腺素 E1 (0.05 g/kg)，持續至肝臟再灌流實驗結束。結果顯示在對照組及給予前列腺素 E1 組，
血清中 ALT 和 AST 的含量顯著低於單獨缺血再灌流組。肝臟的超氧化物歧化含量，在對照組及給予前列腺素 E1
組顯著高於單獨缺血再灌流組。肝臟的一氧化氮含量，在對照組及給予前列腺素 E1 組顯著低於單獨缺血再灌流組。
實驗的結果顯示，在肝臟缺血再灌流時期給予前列腺素 E1 能有效降低肝臟的傷害。[謝政橘、* 邱仁輝、* 吳應寧。
前列腺素 E1 類似物 (Alprostadil) 對於大白鼠肝臟缺血再灌流損傷保護效果之探討。台灣獸醫誌 36 (1)：7-17。* 通訊
作 者，吳 應 寧 TEL：886-2-3366-1302，FAX：886-2-2366-1475，E-mail：wuyl@ntu.edu.tw；邱 仁 輝 TEL：886-2-28267178，FAX：886-2-2822-5044，E-ail：chiujh@mailsrv.ym.edu.tw]