Saldeen K, Nichols W W, Nicolini F, Mehta J
Department of Medicine, University of Florida College of Medicine, Gainesville.
Ups J Med Sci. 1991;96(2):113-8. doi: 10.3109/03009739109179264.
The amino acid L-arginine is a precursor of endothelium derived relaxing factor (EDRF). The pentapeptide 6A (Ala-Arg-Pro-Ala-Lys) released by plasmin degradation of fibrinogen also contains arginine and relaxes vascular smooth muscle by releasing EDRF (nitric oxide). To determine and compare the effects of L-arginine, peptide 6A and a combination of L-arginine and peptide 6A on femoral artery blood flow and vascular resistance, anesthetized mongrel dog were administered saline, L-arginine, D-arginine, peptide 6A and L-arginine + peptide 6A in a random order. L-arginine and peptide 6A both induced an immediate dose-dependent short-lasting increase in femoral blood flow and a decrease in vascular resistance. Peptide 6A exerted a much greater (P less than 0.01) vasodilatory effect than did L-arginine at the same molar concentration suggesting that properties besides the arginine content are important in the effect of the pentapeptide. D-arginine had much less effect than L-arginine, indicating that the effect of L-arginine may be related to its utilization for synthesis of EDRF. When the peptide 6A was given soon after L-arginine, its effect on blood flow was not greater than that of L-arginine alone suggesting that L-arginine in a large amount makes guanylate cyclase less available for the more active peptide.
氨基酸L-精氨酸是内皮衍生舒张因子（EDRF）的前体。纤维蛋白原经纤溶酶降解释放的五肽6A（丙氨酸-精氨酸-脯氨酸-丙氨酸-赖氨酸）也含有精氨酸，并通过释放EDRF（一氧化氮）使血管平滑肌舒张。为了确定并比较L-精氨酸、肽6A以及L-精氨酸与肽6A组合对股动脉血流和血管阻力的影响，对麻醉的杂种犬随机给予生理盐水、L-精氨酸、D-精氨酸、肽6A以及L-精氨酸 + 肽6A。L-精氨酸和肽6A均能立即引起股动脉血流剂量依赖性的短暂增加以及血管阻力降低。在相同摩尔浓度下，肽6A比L-精氨酸具有更强的（P小于0.01）血管舒张作用，这表明除精氨酸含量外的其他特性在该五肽的作用中也很重要。D-精氨酸的作用比L-精氨酸小得多，这表明L-精氨酸的作用可能与其用于合成EDRF有关。当在L-精氨酸后不久给予肽6A时，其对血流的作用并不比单独使用L-精氨酸时更大，这表明大量的L-精氨酸使鸟苷酸环化酶较少可用于更具活性的肽。
