Effects of dietary protein on NO production in the kidney and its evaluation found on food hygiene

体重约200g的Sprague-Dawely大鼠被配对喂食含有低量（6%酪蛋白）蛋白质、正常量（23%酪蛋白）蛋白质或高量（40%酪蛋白）蛋白质的等热量饮食，为期4周。各组大鼠分别行假手术或双侧输尿管梗阻。术后24h，采用筛法分离肾小球，按硫氰酸胍法制备总RNA。采用聚合酶链反应-反转录技术检测一氧化氮合酶(NOS)-1、NOS-2和NOS- 3mrna的表达。对照组（SOC）大鼠肾小球中NOS-1和NOS-3mRNA的表达随饲料蛋白质含量的增加而增加，而在相同条件下NOS-2mRNA未表达。相比之下，双侧输尿管梗阻（BUO）大鼠肾小球中NOS-2mRNA的表达随着膳食蛋白质摄入量的增加而升高。与SOC大鼠相比，BUO大鼠肾小球中NOS-1和NOS-3mRNA的表达降低。因此，高蛋白摄入可能通过降低NOS-1和NOS-3mRNA而使肾小球血流动力学恶化。此外，由于大量自由基NO的生物合成，NOS-2mRNA的增加似乎会通过肾小球损伤使肾小球血流动力学恶化。相反，低蛋白质摄入可能通过抑制NOS-1和NOS-3mRNA的减少和NOS-2mRNA的增加来防止肾小球血流动力学的恶化。

Sprague-Dawely rats Weighing approximately 200g were pair-fed isocaloric diets containing low amounts (6% casein) of protein, normal amounts (23% casein) of protein or high amounts (40% casein) of protein for 4 weeks. Each group of rats underwent sham operation or bilateral ureteral obstruction. Twenty four hours following operation, glomeruli were isolated by sieve techniques and total RNA was prepared according to the method of guanidinium thiocyanate. The expression of nitric oxide synthase (NOS)-1, NOS-2 and NOS-3mRNA was detected using the technique of polymerase chain reaction coupled to reverse transcription. Glomeruli from Shamoperated control (SOC) rats had enhanced expression of NOS-1 and NOS-3mRNA with increases in the amounts of dietary protein while they exhibited no expression of NOS-2mRNA under the same conditions. By contrast, the expression of NOS-2mRNA was angmented with increases in dietary protein intake in glomeruli from rats with bilateral ureteral obstruction (BUO). The expression of NOS-1 and NOS-3mRNA was reduced in glomeruli from rats with BUO when compared to SOC rats. Accordingly, high protein intake may exacerbate glomerular hemodynamics by decreasing NOS-1 and NOS-3mRNA.Also, it appears that increased NOS-2mRNA worsens glomerular hemodynamics via glomerular injury due to the biosynthesis of large amounts of the free radical, NO.Inversely, low protein intake may prevent the deterioration of glomerular hemodynamics by inhibiting a reduction in NOS-1 and NOS-3mRNA and a rise in NOS-2mRNA.