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

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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.