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J Korean Soc Echocardiogr. 1996 Jul;4(1):5-12. Korean. Original Article. https://doi.org/10.4250/jkse.1996.4.1.5
Park CG , Han SW , Lee EM , Jin DG , Kim YH , Yim DS , Seo HS , Shim WJ , Oh DJ , Ro YM .
Department of Internal Medicine, College of Medicine, Korea University, Seoul, Korea.
Abstract

Background

The effects of L-arginine-NO system on myocardial stunning haven't been well known. This work was designed to know whether L-arginine, physiologic NO precusor, would attenuate postischemic myocardial dysfunction or not. To investigate whether intravenous administration of L-arginine, physiological nitric oxide(NO) precursor, during reperfusion would attenuate postischemic myocardial dysfunction, 18 open-chest dogs were studied.

Methods

In 18 pentobarbital anesthesized open-chest dogs, left circumflex coronary artery was occluded for 20 minutes and was followed by a reperfusion for 60 minutes. L-Arginine(30mg/kg)(L-arginine group, n=8) or saline(control group, n=10) was infused intravenously 1 minute before reperfusion and was followed by a continuous infusion (10mg/kg/min) for 30 minutes during reperfusion. Before coronary occlusion and 30 minutes and 60 minutes after reperfusion, coronary blood flow(CBF) and coronary vascular resistance(CVR) were measured. Myocardial segment thickening in the area of ischemia-reperfusion was measured using 2D-echocardiography. The echocardiography images were digitized and analyzed by cardiac image analyzer.

Results

1) Percent change of CBF was decreased by 42.5% in L-arginine group but it was increased by 1.3% in control group(p=0.025) and %change of CVR was increased by 83.5% in L-arginine group vs 11% in control group after 60 minutes of reperfusion, compared with pre-occlusion baseline values(p=0.06). 2) Percent change of myocardial segment thickening was decreased both in L-arginine group(by 69.5%) and control group(by 57.6%) after reperfusion 30 minutes without statistically significance, but it was significantly decreased in L-arginine group(by 80%) compared with control group(by 55.6%) after reperfusion 60 minute(p=0.01).

Conclusion

The findings that the administration of L-arginine cause significant depression of post-ischemic myocardial contractile function after reperfusion 60 minutes suggests that systemic infusion of L-arginine has an unfavorable effect on myocardial stunning and low reflow phenomenon. These results suggest that L-arginine may have independent deteriorating effects on myocardial stunning after reperfusion 60 minutes.

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