Alton, Eric W.

Frass, Oliver M.

Geddes, Duncan M.

Heinl-Green, Amanda

Post, Mark

Radke, Peter W.

Elsevier - Publisher Connector 

Evaluation of the porcine ameroid constrictor model of chronic myocardial ischemia for therapeutic angiogenesis studies 

JACC March 19,2003 ABSTRACTS - Myocardial Ischemia and Infarction 331A 
raw aorta were then removed and subsequent aoriic ring vasorelaxation response to 
acetylcholine (ACh) was measured with and wlthout L-NMMA, an inhibitor of NO synthe- 
sis. Endothellal NO synthetase (eNOS) protein levels were measured from the harvested 
left ventricles using standard immunoblot techniques. MI rats treated with spironolactone 
had a decreased (PcO.05) systolic blood pressure (SBP, 128 * 22 vs 111 * 10 mmHg), 
and mean arierlal pressure (MAP, 111 * 23 vs 92 + 11 mmHg) compared to MI untreated 
rats. There was no difference in left ventricular (LV) dP/dt (LV dP/dt, 5600 + 1889 vs 
4681 f 696 mmHg/sec) and LV end diastolic pressure. LVEDP (LVEDP, 16 * 7 vs 21 + 6 
mmHg) in Ml untreated animals compared to MI rats treated with spironolactone. Com- 
pared to Ml untreated rats, spironolactone improved (P~0.05) endothelial dependent 
vasorelaxation at a concentration of 10.’ M ACh and greater. This improvement in endot- 
helial dependent vasorelaxatlon was attenuated in the presence of L-NMMA. Endotheltal 
NOS protein levels were attenuated (P<O.O5) in Ml (48.7+ 17 vs 15.1 -+ 7 intensity units/ 
pg tissue) compared to sham rats. Ml rats treated with spironolactone had an increase 
(PcO.05) in eNOS protein levels (42.82 5 vs 15.1 -+7 intensity unitsipg tissue) compared 
to Ml untreated. Our study demonstrate that spirolactone improved NO mediated endot- 
helial dependent vasorelaxation m heart failure by increasing eNOS protein levels. 
1024-l 11 Evaluation of the Porcine Amerold Constrictor Model of 
Chronic Myocardial lschemia for Therapeutic 
Angiogenesis Studies 
Peter W. Radke, Amanda Heinl-Green, Oliver M. Frass, Mark Post, Duncan M. Geddes. 
Eric W. Alton, Imperial College London, London, United Kingdom 
Background: The porcine model of chronic myocardial ischemia is widely used for pre- 
clinical testing of angiogenic genes and proteins. Important characteristics of this model 
like the impact of target vessel occlusion on the presence of myocardial ischemia as well 
as the relation between morphological, functional. and hemodynamic measurements, 
however, have not been described in detail. 
Methods: We performed a systematic analysis of 94 study animals undergoing ameroid 
constrictor placement around the left circumflex coronary artery (LCX). Pigs underwent a 
comprehensive evaluation Including echocardiography. coronary angiography and myo- 
cardial blood flow measurements at rest/ stress 26*5 days after ameroid placement. 
Results: Complete occlusion of the LCX was obsewed in 34194 (36%) animals who dem- 
onstrated myocardial &hernia of the lateral wall at rest and under stress conditions. By 
applying a set of angiographic criteria (TIMI< flow in LCX or collateral flow Rentrop 
class .I) another 29% (27/94) of study animals with myocardial &hernia under pharma- 
cological stress conditions could be identibed. Echccardiographic parameters of regional 
and global myocardial function were not associated with myocardial blood flow or the 
level of &hernia. There was. however, a strong correlation between fractional shortenmg 
and the left atrial pressure as a surrogate for cardiac preload (R= -0.36, p=O.O05). There 
was no relation between the extent of coronary cotlateralisation as assessed by angiog- 
raphy and echocardlographic parameters or myocardial blood flow. 
Conclusion: Occlusion of the ameroid instrumented coronary artery is not a pre-requisite 
for successfully establishing the pathophysiology of chronic myocardial ischemia. The 
above defined angiographic criteria are useful in identifylog animals wth appropriate 
Ischemia, despite incomplete LCX occlusion. The left atrial pressure as a surrogate of 
cardiac preload serves as a valuable predictor of regional myocardial function. 
1024-1’12 Diabetes, Hyperglycemia, GIK, and Cardioprotection: 
Do ATP-Regulated Potassium Channels Play a Role? 
John F. LaDisa. Jr. John G. Krolikowski, Lynda M. Ludwig, Paul S. Pagel, David C 
W&tier, Judy R. Kersten, Medical College of Wisconsin, Milwaukee, WI, Marquette 
University Milwaukee, WI 
Background: Insulin is protectwe, whereas, hyperglycemia is deleterious during myo- 
cardial ischemia and reperfusion injury. Diabetes and hyperglycemia attenuate. but insu- 
lin activates ATP-regulated potassium (hTP) channels. We tested the hypothesis that 
blockade of K,,TP channels with pharmacological antagonists or hyperglycemia before 
ischemia abolishes reductions of myocardial infarct size produced by GIK on reperfusion. 
Methods: The temporal dependence of cardioprotection was investigated in barbiturate- 
anesthetized dogs (n=7 in each group) randomly assigned to receive GIK (25% dextrose; 
50 IU insulin/L; 80 mM/L KCI infused at 1.5 mlJkg/hr) starting 75 minutes before coronary 
artery occlusion or five minutes before reperfusion. The role of K,,, channels in the car- 
dioprotective effects of GIK were evaluated in dogs pretreated with glyburlde (0.1 mg/kg 
IV). The efficacy of GIK was further Investigated by increasing blood glucose concentra- 
tion to 100, 300, or 600 mg/dL (intravenous dextrose) or in diabetic dogs (3 weeks after 
alloxan-streptozotocin). 
Results: There were no differences in area at risk (AAR) or collateral blood flow among 
groups. Myocardial infarct size (triphenyltetrazolium staining) was 28&2% of the AAR in 
control dogs. GIK significantly (PcO.05) decreased Infarct size when administered at rep- 
erfusion independent of blood glucose concentration (13~2 and 12+2%; 100 and 600 
mg/dL, respectively). The protective effects of GIK upon reperiusion were abolished in 
diabetic animals (25*3%), animals receiving glyburide (30r5%). and in those subjected 
to hyperglycemia before ischemia (27*4%; 600 mg/dL). GIK did not protect against inf- 
arction when administered before lschemia (31+3, 27+2 and 3553% during blood glu- 
cose concentrabons of 100, 300. and 600 mg/dL, respectwely). 
Conclusion: The insulin component of GIK and not glucose is responsible for reductions 
of infarct size when GIK is administered during repeffusion. This action IS K,,,-depen- 
dent and blocked by glyburide. In contrast, glucose decreases I&? channel activity, and 
this effect predominates over that of insulin if hyperglycemia is present before ischemia. 
1024-113 Ozone Reduces Reperfusion Injury in an Isolated Rat 
Heart Model 
Ofer Merin, Eyal At&s, Ari Zimran, Debbie Elstein, Gerhard Wasser, Herzl Schwalb, Dani 
Bitran, Shuli Silberman, Shaare Zedek Medical Center, Jerusalem, Israel, Hadassah 
Medical Center, Jerusalem. Israel 
Background: Ozone has been used for various clinical conditions associated with 
ischemia, inflammation or infection. Although there are numerous reports claiming bene- 
ficial effects, administration of ozone has remained largely in the realm of alternative 
medicine. We studied the effects of ozone on reperfusion injury in an isolated rat heart 
model. 
Methods: Twenty six Sprague- Dawley rat hearts randomized to control (n=l3) or treat- 
ment group (n=13) were perfused with modified Krebs-Henseleit buffer at 37 degrees 
centigrade and a constant pressure of 90 cm H20. A latex balloon tipped catheter was 
inserted into the left ventricular cavity to assess contractile function. After 15 minutes of 
perfusion, the hearts were subject to 30 minutes of Ischemia, after which reperfusion was 
initiated for 40 minutes during which data was collected every 10 minutes. HealtS with 
the following pre-ischemic parameters were excluded: heart rate <ZOO; or left ventricular 
developed pressure (LVDP) (calculated by end systolic pressure minus end diastolic 
pressure) <SO or ~250. Thus there were I3 in the control group and 11 in the treatment 
group. Ozone was produced in a Dr. Hansler generator PM84 at a concentration of 30 
ucgrlcc, and adminlstered in the treatment group after 5 minutes of reperfusion, in dis- 
tilled water via a sidearm, at a rate of 0.17 cc/minute for a total of 0.85 cc. Heart rate, cor- 
onary flow, dP/dt max, and LVDP were measured. 
Results: There was no difference in preischemic baseline measurements between the 
two groups. Nor was there any difference in coronary flow. Hearts perfused with ozone 
exhibited a signiftcantly better post-ischemic recovery: 61% vs 44% I” controls (p=O.Ol). 
Conclusions: Our results show a beneficial effect of ozone I” repedusion of an isolated 
rat heart model. This is possibly due to a scavenging of free radicals, thus reducing rep- 
eriusion injury. Further studies in a large animal model are warranted in order to deter- 
mine the therapeutic potential of ozone in the setting of myocardial ischemia. 
1024-114 In Vivo Myocardial Gene Transfer of Dominant Negative 
IKK-j3 Reduces Injury in Ischemia-Reperfusion but Not 
Straight Infarction 
Younakeun Ah4 Mlkhail Novikov, Steffen Meiler, Takashl Matsui. Anthony Rosenzweig. 
Massachusetts General Hospital, Charlestown, MA 
Background: NF-nB transcription factors drive expression of many genes involved in 
inflammation and cell survival, both important in ischemia-reperfuslon (IR) injury. IKK-!j 
can mediate NF& activation through phosphorylation of k%, however, alternative path- 
ways of activation exist. 
Methods: To test the role of lKK$ signaling in cardiac injury, we performed cardiac gene 
transfer of dommant negative IKKP (dnlKK-P) in rats 48 hr prior to IR (30 min I; 24 hr R) 
or infarction wthout reperfusion (MI). 
Results’ We found that adenoviral gene transfer resulted in regional transgene expres- 
sion comprising -60% of the ischemic area. Ad.dnlKK-P reduced IR-induced NFa% 
translocation and t&r degradation, and blocked induction of the NF-rB-dependent 
inflammatory chemokine, MCP-1, in the ischemic area compared with Ad.EGFP$-gal 
treated rats (pcO.05). The number of mfiltrating neutrophils and myeloperoxidase activity 
in the ischemic area were decreased in Ad.dnlKKj?-treated rats compared with 
Ad.EGFP.@gal-treated rats (~~0.05). The ischemic area was not affected by dnlKK-P 
expression. However, in IR, Ad.dnlKKQ reduced infarct area by 57% compared with 
Ad.EGFP.egal treated rats or buffer alone (pcO.001). In contrast, in straight MI, dnlKK-P 
did not affect infarct area (p=NS). 
Conclusion: In wvo gene transfer of dnlKK-p prevents IR-induced activation of NF-rB. 
In this setting, abrogation of pro-inflammatory signals appears more important than loss 
of NF-KB dependent Survival factors, resulting in an overall reduction in Infarct size. In 
contrast, in straight MI, IKK-P-dependent signals do not appear to contribute to injury. 
These data suggest that IKK-P may represent a valuable target for therapeutic mterven- 
tion in IR ~njuty. 
1024-115 A New Model of Coronary Microthrombosis in Rats and 
the Protective Effect of a New Thrombin Inhibitor 
Chenoxina Shen Junbo Ge. Llanglong Chew Qingyong Zhang, Yukun Luo, Chun Llang, 
Shuangjie Li. Hao Zhu Chen, Houyan Song, Wei MO. Duan Ma, Zhongshan Hospital of 
Fudan University, Shanghai, People’s Republic of China. Fudan Unwersity, Shanghai, 
People’s Republic of China 
BACKGROUND AND 0BJECTIVE:Minor myocardial infarction after interventional treat- 
ment is not uncommon in the clinic.The aim of this study was to develop a new model of 
minor myocardial infarction based on endothelial damage and thrombotic occlusion in 
coronary artery, leading to small myocardlal infarcts in rats. Moreover, the protective 
effect of r-RGD-Hirudin, a thrombin inhibitor, was investigated in this model. METHODS: 
Forty eight male Sprague-Dawley rats were used I” the present study. Rats were anes- 
thetized with sodium pentobarbital and ketamine, and 200 ug of sodium laurate was 
injected into the coronary artery. The thrombus induction and consequent of endothelial 
damage were examined by histopathological analyses and electron microscope. To 
investigate the protective effects of r-RGD-Hirudin,l or 5 mg/kg was administered intrap- 
erltoneally 5 minutes after the Injection of sodium laurate;the control group was injected 
saline instead. RESULTS: Three hours after the injection of sodium lawate, microscopic 
examnation of phosphotungstic acid hematoxylin-stained sections (n=8) and Carstairs 
Stain sections(n=8) revealed that microthrombi containing fibrin strands obstructed the 
pertorating arteries in the myocardium. Under a transmission electron microscope (n=5), 
endotheltal cells appeared exfoliated and the vascular lumen was obstructed by a throm- 
bus composed of degranulated platelets, fibrin, leukocytes, and erythrocytes. Multiple 


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Evaluation of the porcine ameroid constrictor model of chronic myocardial ischemia for therapeutic angiogenesis studies

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