Supplemental l-arginine during cardioplegic arrest and reperfusion avoids regional postischemic injury,☆☆,,★★,

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Abstract

Unenhanced hypothermic cardioplegia does not prevent postischemic endothelial and contractile dysfunction in hearts subjected to antecedent regional or global ischemia. This study tested the hypothesis that supplementing blood cardioplegic solution and reperfusion with the nitric oxide precursor l-arginine would preserve endothelial function, reduce infarct size, and reverse postcardioplegia regional contractile dysfunction by the L-arginine-nitric oxide pathway. In 23 anesthetized dogs, the left anterior descending coronary artery was ligated for 90 minutes, after which total bypass was established for surgical “revascularization.” In 10 dogs, unsupplemented multidose hypothermic blood cardioplegic solution was administered for a total of 60 minutes of cardioplegic arrest. In eight dogs, L-arginine was given intravenously (4 mg/kg per minute) and in blood cardioplegic solution (10 mmol) during arrest. In five dogs, the nitric oxide synthesis blocker N ω-nitro-L-arginine (1 mmol) was used to block the L-arginine–nitric oxide pathway during cardioplegia and reperfusion. Infarct size (triphenyltetrazolium chloride) as percent of the area at risk was significantly reduced by L-arginine compared with blood cardioplegic solution (28.2% ± 4.1% versus 40.5% ± 3.5%) and was reversed by N ω-nitro-L-arginine to 68.9% ± 3.0% (p < 0.05). Postischemic regional segmental work in millimeters of mercury per millimeter (sonomicrometry) was significantly better with l-arginine (92 ± 15) versus blood cardioplegic solution (28 ± 3) and N ω-nitro-L-arginine (26 ± 6). Segmental diastolic stiffness was significantly lower with L-arginine (0.46 ± 0.06) compared with blood cardioplegic solution (1.10 ± 0.11) and was significantly greater with N ω-nitro-l-arginine (2.70 ± 0.43). In ischemic-reperfused left anterior descending coronary arterial vascular rings, maximum relaxation response to acetylcholine, the stimulator of endothelial nitric oxide, was depressed in the blood cardioplegic solution group (77% ± 4%) and was significantly reversed by L-arginine (92% ± 3%). Smooth muscle function was unaffected in all groups. We conclude that cardioplegic solution supplemented with L-arginine reduces infarct size, preserves postischemic systolic and diastolic regional function, and prevents arterial endothelial dysfunction via the L-arginine–nitric oxide pathway. (J THORAC CARDIOVASC SURG 1995;110:302-14)

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From the Departments of Cardiothoracic Surgerya and Physiology/Pharmacology,b Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, N.C.

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Supported in part by grant HL46179 from the National Heart, Lung and Blood Institute of the National Institutes of Health.

Address for reprints: Jakob Vinten-Johansen, PhD, Department of Cardiothoracic Surgery, Bowman Gray School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1096

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