Braam B, Koomans H A
Department of Nephrology and Hypertension, University Hospital Utrecht, The Netherlands.
Kidney Int. 1995 May;47(5):1252-7. doi: 10.1038/ki.1995.179.
Previous studies indicate that endothelium-derived nitric oxide (NO) can directly modulate afferent arteriolar tone and that macula densa-derived NO can indirectly regulate afferent arteriolar tone by modulating the tubuloglomerular feedback (TGF) mechanism. The present in vivo micropuncture study evaluated whether the effect of late proximal tubular perfusion with the nitric oxide synthase (NOS) inhibitor, NG-L-arginine (NLA), on TGF responsiveness is related to reabsorption of NLA. Late proximal perfusion of 10(-3) M NLA resulted in a gradual, time-dependent enhancement of maximum TGF-mediated decreases in stop-flow pressure (SFP) from -7.1 +/- 0.7 to -19.4 +/- 1.6 mm Hg (P < 0.01). A detailed recording of SFP revealed that the maximum response during late proximal perfusion of NLA was obtained eight to nine minutes following the initiation of the perfusion, whereas maximum TGF responses evoked by late proximal perfusion with ATF were reached within one to two minutes. NLA infused into the late proximal segment of a neighboring nephron also resulted in enhancement of maximum SFP feedback responses from -5.5 +/- 0.5 to -10.4 +/- 1.9 mm Hg (P < 0.05), indicating that NLA can be reabsorbed and can consequently influence TGF responses. Finally, maximum SFP feedback responses were obtained prior to and following late proximal perfusion of 10(-3) M NLA dissolved in ATF, 10(-3) M NLA dissolved in 285 mM mannitol, and following perfusion with mannitol without NLA.(ABSTRACT TRUNCATED AT 250 WORDS)
先前的研究表明，内皮衍生的一氧化氮（NO）可直接调节入球小动脉张力，而致密斑衍生的NO可通过调节管球反馈（TGF）机制间接调节入球小动脉张力。本体内微穿刺研究评估了用一氧化氮合酶（NOS）抑制剂NG-L-精氨酸（NLA）对晚期近端肾小管进行灌注，其对TGF反应性的影响是否与NLA的重吸收有关。用10⁻³ M NLA对晚期近端肾小管进行灌注，导致TGF介导的最大停流压力（SFP）降低逐渐增强，且呈时间依赖性，从-7.1±0.7 mmHg增至-19.4±1.6 mmHg（P<0.01）。对SFP的详细记录显示，在灌注NLA的晚期近端肾小管期间，最大反应在灌注开始后八至九分钟出现，而晚期近端肾小管灌注ATF所诱发的最大TGF反应在一至两分钟内达到。将NLA注入相邻肾单位的晚期近端节段，也导致最大SFP反馈反应增强，从-5.5±0.5 mmHg增至-10.4±1.9 mmHg（P<0.05），表明NLA可被重吸收，从而影响TGF反应。最后，在晚期近端肾小管灌注溶解于ATF的10⁻³ M NLA、溶解于285 mM甘露醇的10⁻³ M NLA以及灌注不含NLA的甘露醇之前和之后，均获得了最大SFP反馈反应。（摘要截选至250字）
