Maccario M, Oleandri S E, Procopio M, Grottoli S, Avogadri E, Camanni F, Ghigo E
Dipartimento di Medicina Interna, Università di Torino, Italy.
J Endocrinol Invest. 1997 Sep;20(8):488-92. doi: 10.1007/BF03348006.
Arginine has well-known stimulatory effects on GH, PRL and insulin secretion in man but the mechanisms underlying these effects are still unclear. More recently, it has been demonstrated that arginine is the precursor of nitric oxide (NO) which mediates its vasodilatatory effect. Thus, it has been hypothesized that NO could also mediate the hormonal effects of arginine. To clarify this point, in seven normal young volunteers (7 normal male subjects, age 26-35 yr) we compared the effects of arginine hydrochloride (ARG, 0.5 g/kg iv over 30 min) on GH, PRL, insulin and glucose levels as well as on blood pressure, with those of isosorbide dinitrate (ISDN, 5 mg po) and molsidomine (MOLS, 4 mg po), two NO donors which possess well-known vasodilatatory effects. ARG infusion elicited a clear-cut GH increase (peak vs baseline 17.6 +/- 4.7 vs 2.7 +/- 0.8 (g/L, p < 0.01), PRL (20.6 +/- 2.8 vs 6.9 +/- 0.5 (g/L, p < 0.01) and insulin levels (31.4 +/- 5.7 vs 4.5 +/- 2.1 (U/L, p < 0.01) while induced a biphasic variation of plasma glucose levels with early increase (p < 0.01), followed by late decrease below basal values (p < 0.01). On the other hand, blood pressure was decreased by ARG (nadir vs baseline; systolic: 103 +/- 6 vs 112 +/- 3, p < 0.02 and diastolic 61 +/- 4 vs 72 +/- 2 mmHg, p < 0.02, respectively). ISDN and MOLS did not modify basal GH, PRL and insulin as well as glucose levels while induced a clear reduction in blood pressure (ISDN: nadir vs baseline; systolic: 94 +/- 4 vs 112 +/- 2, p < 0.02; diastolic 69 +/- 3 vs 80 +/- 2, p < 0.02; MOLS: systolic: 94 +/- 3 vs 113 +/- 2 p < 0.02; diastolic 63 +/- 4 vs 72 +/- 2, p < 0.02). The lowering effect of both ISDN and MOLS on both systolic and diastolic blood pressure levels was higher than that induced by ARG. The effect of the latter was, in turn, significantly different from that of placebo on diastolic levels only. In conclusion, our present date are against the hypothesis that NO mediates the stimulatory effects of arginine on GH, PRL and insulin secretion. On the other hand, our findings agree with the hypothesis that ARG has NO-mediated vasodilatatory effect able to decrease blood pressure in man.
精氨酸对人体生长激素（GH）、催乳素（PRL）和胰岛素分泌具有众所周知的刺激作用，但其作用机制仍不清楚。最近，有研究表明精氨酸是一氧化氮（NO）的前体，后者介导其血管舒张作用。因此，有人推测NO也可能介导精氨酸的激素效应。为了阐明这一点，我们对7名正常年轻志愿者（7名正常男性受试者，年龄26 - 35岁）进行了研究，比较了盐酸精氨酸（ARG，0.5 g/kg静脉注射，持续30分钟）对GH、PRL、胰岛素和血糖水平以及血压的影响，与硝酸异山梨酯（ISDN，5 mg口服）和吗多明（MOLS，4 mg口服）这两种具有众所周知血管舒张作用的NO供体的影响。输注ARG可使GH明显升高（峰值与基线相比：17.6±4.7 vs 2.7±0.8 μg/L，p<0.01）、PRL升高（20.6±2.8 vs 6.9±0.5 μg/L，p<0.01）和胰岛素水平升高（31.4±5.7 vs 4.5±2.1 U/L，p<0.01），同时使血浆葡萄糖水平出现双相变化，早期升高（p<0.01），随后晚期降至基线值以下（p<0.01）。另一方面，ARG可使血压降低（最低点与基线相比；收缩压：103±6 vs 112±3，p<0.02；舒张压：61±4 vs 72±2 mmHg，p<0.02）。ISDN和MOLS对基础GH、PRL、胰岛素以及血糖水平无影响，但可使血压明显降低（ISDN：最低点与基线相比；收缩压：94±4 vs 112±2，p<0.02；舒张压：69±3 vs 80±2，p<0.02；MOLS：收缩压：94±3 vs 113±2，p<0.02；舒张压：63±4 vs 72±2，p<0.02）。ISDN和MOLS对收缩压和舒张压水平的降低作用均高于ARG。后者的作用仅在舒张压水平上与安慰剂有显著差异。总之，我们目前的数据不支持NO介导精氨酸对GH、PRL和胰岛素分泌的刺激作用这一假说。另一方面，我们的研究结果支持精氨酸具有NO介导的血管舒张作用从而能够降低人体血压这一假说。
