S21Abstracts / Cell Biology International 32 (2008) S1eS67

The aim of this study was to investigate the mechanism of cardioprotective ef-

fects of diazoxide, a selective opener of mitochondrial ATP-sensitive potas-

sium channel (mitoKATP) in preserved heart. The isolated rat heart

Langendorff model was used. The hearts were stored in 4�C Celsior solution

in the presence or absence of diazoxide for 3, 6 or 9 h followed by 60 min of

reperfusion. Apoptotic cardiomyocytes were detected by terminal deoxynu-

cleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) method.

The expression of heat shock protein 70 (HSP 70) was also evaluated by west-

ern blotting analysis. The results showed that the percentage of apoptotic cells

increased in a time-dependent manner after hypothermic preservation. When

compared with the 9 hours control group, diazoxide (15, 30 or 45 mmol/L) re-

duced the percentage of apoptotic cells and increased the expression of HSP

70 protein in rat hearts suffered from 9 hours of hypothermic preservation

in a dose-dependent manner. These results indicate that diazoxide could alle-

viate rat myocardial injury induced by ischemia- reperfusion through upregu-

lation of HSP 70 protein expression. (This work was supported by the National

Natural Science Foundation of China (No.30470635)).

ELEVATED ASYMMETRIC DIMETHYLARGININECONTRIBUTES TO THE HEPATIC MITOCHONDRIALDYSFUNCTION OF STREPTOZOTOCIN-INDUCEDDIABETIC RATSNa Chen, Yu Ting Zhao, Yi Ping Leng, Zhong Zu Wu, Yan Xiong*

Department of Pharmacology, School of Pharmaceutical Sciences,Central South University, Changsha 410078, Hunan, P. R. ChinaMitochondrial dysfunction is one of the characteristics in diabetes mellitus.

Accumulating evidence showed that endogenous nitric oxide synthase

(NOS) inhibitor asymmetric dimethylarginine (ADMA) played important roles

in insulin resistance, diabetes and diabetic vascular complications. This study

was to explore the roles of ADMA in the development of hepatic mitochon-

drial dysfunction in diabetic rat and its potential mechanisms. Diabetic model

was induced by a single injection of streptozotocin (60 mg/kg) to male

Sprague-Dawley rats. Serum ADMA levels were analysed by high perfor-

mance liquid chromatography. Mitochondrial transmembrane potential, ATP

content, succinate dehydrogenase and cytochrome C oxidase activities in dia-

betic rat liver and ADMA-treated hepatocytes were measured to evaluate mi-

tochondrial function. Copy numbers of mitochondrial gene COX I and nuclear

gene b-actin were used to reflect mitochondrial biogenesis. UCP2 and PGC-1a

transcriptions, NOS and SOD activities, nitrite/nitrate and malondialdehyde

contents were detected to explore the mechanisms of hepatic mitochondrial

dysfunction induced by ADMA. Results showed that serum endogenous

ADMA levels were elevated in accompany with impaired hepatic mitochon-

drial function as shown by the reductions of mitochondrial membrane poten-

tial, ATP production, succinate dehydrogenase and cytochrome C oxidase

activities, and mitochondrial biogenesis in diabetic rats. Similar mitochondrial

dysfunction was observed in cultured hepatocytes (H4IIE) after exposure to

exogenous ADMA. Treatment with antioxidant PDTC not only improved mi-

tochondrial function but also increased mitochondrial biogenesis. Further stud-

ies revealed that hepatic mitochondrial dysfunction induced by ADMA was

associated with enhancements of UCP2 transcription and oxidative stress.

These results suggest that the elevation of endogenous ADMA contributed

to hepatic mitochondrial dysfunction in diabetic rats through increasing

oxidative stress and upregulating UCP2 transcription. This study was sup-

ported by grant from the Natural Science Research Foundation of China

(30271507).

MMP-2, 9 EXPRESSION ON ATHEROSCLEROTIC PLAQUEIN apoE OR LDLR KNOCKOUT MICE WITH ANDWITHOUT CHOLESTEROL DIETJun Zhou 1, Ling Ling Zhao 1, Satoru Ohshima 2,Shinichiro Fujimoto 2, Ai Fujimoto 2, Artiom Petrov 2,Jagat Narula 2

1 The Third Xiangya Hospital, Central South University XiangyaSchool of Medicine, Changsha, Hunan Province, China

2 Division of Cardiology, University of California, Irvine School ofMedicine, Irvine, California, USAMatrix metalloproteinases (MMPs) are an ever-expanding family of endopep-

tidases with common functional domains and mechanisms of action discov-

ered because of their ability to degrade ECM components. MMP activity is

thought to be regulated at multiple levels: the growth, destabilization, and

eventual rupture of atherosclerotic lesions. Apolipoprotein E knockout

(ApoE-/-) and low-density lipoprotein receptor knockout (LDLR-/-) mice

exhibit hypercholesterolemia and develop complex atherosclerotic lesions

similar as human. Using these ApoE-/- and LDLR-/- mice model with and

without cholesterol diet, C57BL/6 mice served as controls, we evaluated the

role of MMP-2, 9 on atherosclerotic lesion. Histological and histochemical

observations of atherosclerosis revealed significant correlation of MMP-2, 9

express with macrophage and smooth muscle cell. ApoE-/- and LDLR-/-

mice with cholesterol diet exhibited cellular compositional changes indicative

of an unstable plaque phenotype and had the high MMP-2, 9 express. Com-

pared with these mice, ApoE-/- and LDLR-/- mice without cholesterol diet

had reduced lesion size and increased smooth muscle cell and decreased mac-

rophage content in the plaque, indicative of a stable plaque phenotype. These

data demonstrate high cholesterol diet effect MMP-2, 9 express in macro-

phages and degrade vascular matrix directly involved in atherosclerotic plaque

destabilization.

EFFECT OF NITRIC OXIDE SYNTHASE INHIBITORS ONHEMODYNAMIC PARAMETERS AND THORACIC AORTATENSION IN SEPTIC SHOCK RATSXin Mei Zhou 1,2, Man Li Xia 1,2, Min Wang 1, Ce Xu 2, Qiang Xia 2

1 Department of Physiology, Jiaxing University School of Medicine,Jiaxing, China2 Department of Physiology, Zhejiang University School of Medicine,Hangzhou, ChinaThe present study was to investigate the effect of nitric oxide synthase inhib-

itors on hemodynamic parameters and thoracic aorta tension in septic shock

rats. We used cecal ligation and puncture (CLP) method to establish septic

shock in rats, and nitric oxide synthase inhibitors (L-NAME, AMG or

7-NI) were injected after CLP. The carotid artery was cannulated and con-

nected to a pressure transducer to determine mean arterial blood pressure

(MABP). Ventricular dynamic parameters, including heart rate (HR), left

ventricular developed pressure (LVDP), maximal rise/fall velocity of ventric-

ular pressure (+/-dP/dtmax), were determined following intraventricular can-

nulation via the carotid artery. Isolated thoracic rings were mounted on the

organ bath and the tension of the vessel was recorded. We found that (1) af-

ter treatment with L-NAME, AMG or 7-NI, the mortality decreased to 50.0

%, 37.5 %, and 42.1 %, respectively (65.2 % in septic shock rats); (2) the

MABP in septic shock rats partly recovered after using the NOS inhibitors,

and all ventricular dynamic parameters partly recovered after using the in-

hibitors; (3) the hyporeactivity of endothelium-denuded aortic rings to vaso-

constrictors induced by septic shock was partly recovered by pretreatment

with the inhibitors. However, only L-NAME or 7-NI could inhibit the

decrease of vasoconstriction induced by septic shock in endothelium-intact

aortic rings. The results indicate that the three nitric oxide synthase inhibi-

tors had different improved effects on hemodynamic parameters and thoracic

aorta tension in septic shock rats, which may be related to the specificity of

the inhibitors.

STEM CELL RESEARCH AND INJURY REPAIR

A NOVEL ISOLATED SUBPOPULATION OF BONEMARROW STEM CELLLiang Cao 1,2, Zhen Li 1, Yin Yu Mao 1,2, Xiao Tao Shen 1,2,Xin Zheng 1, Yao Yao 1,2, Jiang Wang 1, Lin Lin Zhang 1, DongQing Cai* 1,2

1 Joint Laboratory for Regenerative Medicine, The ChineseUniversity of Hong Kong-Ji Nan University