Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia, USA.
Pediatr Res. 2012 Feb;71(2):144-9. doi: 10.1038/pr.2011.23. Epub 2011 Dec 21.
Nitric oxide (NO) vasodilation critically modulates renal hemodynamics in the neonate compared with the adult. Based on the postnatal expression pattern of renal neuronal nitric oxide synthase (nNOS), the hypothesis was that nNOS is the major NOS isoform regulating renal hemodynamics in the immature, but not mature, kidney.
NOS inhibitors did not alter mean arterial pressure (MAP) in either group. Intrarenal S-methyl-L-thiocitrulline (L-SMTC) in newborns significantly reduced renal blood flow (RBF) 38 ± 4%, glomerular filtration rate (GFR) 42 ± 6%, and increased renal vascular resistance (RVR) 37 ± 7%, whereas intrarenal L-nitro-arginine methyl ester (L-NAME) affected RBF, GFR, and RVR equivalent to L-SMTC treatment. When L-NAME was administered after L-SMTC treatment, newborn renal hemodynamic changes were not further altered from what was observed when L-SMTC was administered alone. In contrast, in the adult, only intrarenal L-NAME, and not L-SMTC, affected renal hemodynamic responses.
In conclusion, these studies demonstrate that nNOS is an important regulator of renal hemodynamics in the newborn kidney, but not in the adult.
Experiments compared renal hemodynamic responses with intrarenal infusion of L-NAME, an inhibitor of all NOS isoforms, with the selective nNOS inhibitor L-SMTC in the newborn piglet and the adult pig.
与成人相比，一氧化氮（NO）血管舒张在新生儿中对肾脏血液动力学有重要的调节作用。基于肾脏神经元型一氧化氮合酶（nNOS）的出生后表达模式，提出假设：nNOS 是调节未成熟肾脏血液动力学的主要 NOS 同工酶，但不是成熟肾脏的主要 NOS 同工酶。
NOS 抑制剂在两组中均未改变平均动脉压（MAP）。内源性 S-甲基-L-硫代瓜氨酸（L-SMTC）在新生儿中显著降低肾血流量（RBF）38±4%，肾小球滤过率（GFR）42±6%，并增加肾血管阻力（RVR）37±7%，而内源性 L-硝基-精氨酸甲酯（L-NAME）对 RBF、GFR 和 RVR 的影响与 L-SMTC 治疗相当。当 L-NAME 在 L-SMTC 处理后给予时，新生儿肾脏血流动力学变化与单独给予 L-SMTC 时观察到的变化没有进一步改变。相比之下，在成人中，只有内源性 L-NAME，而不是 L-SMTC，影响肾脏血液动力学反应。
总之，这些研究表明 nNOS 是新生儿肾脏血液动力学的重要调节因子，但不是成人肾脏的重要调节因子。
实验比较了内源性给予 L-NAME（一种所有 NOS 同工酶的抑制剂）和选择性 nNOS 抑制剂 L-SMTC 在新生仔猪和成年猪中的肾脏血液动力学反应。
