Müller-Suur R, Ulfendahl H R, Persson A E
Am J Physiol. 1983 Apr;244(4):F425-31. doi: 10.1152/ajprenal.1983.244.4.F425.
To determine whether the filtration rate of juxtamedullary nephrons is regulated by tubuloglomerular feedback (TGF), we developed two micropuncture techniques suitable for the papilla of young rats. One consisted of measuring the tubular flow in descending limbs of Henle loops (VDLH) while the ascending limbs of the loop of Henle (ALH) were perfused at various rates with three different solutions: modified Ringer, artificial Henle loop solution, and Ringer containing 10(-4) M furosemide. SNGFR was also measured in several juxtamedullary nephrons. The other protocol consisted of measuring the tubular stop-flow pressure (PSF) in descending limbs of the loop of Henle upstream to a wax block. Distal to the block Ringer was perfused at various rates through ALH. Our results provide the first evidence of a TGF response in juxtamedullary nephrons. VDLH and SNGFR decreased during Ringer perfusion to 42 +/- 4 and 44 +/- 4% of their values at zero perfusion. The same pattern was observed using Henle loop solution as perfusate, whereas with furosemide VDLH did not change. The maximal decrease in PSF was 14.1 +/- 1.4 mmHg. The perfusion rate necessary to induce a half-maximal PSF decrease was 9.1 +/- 0.9 nl/min. Similar micropuncture techniques were used in proximal tubules of surface nephrons in these rats, which in comparison to the deep nephrons showed smaller feedback responses. The mechanism seems to be active at physiological nephron flow rates in both nephron populations. Thus, TGF can exert its effect on GFR of the whole kidney by acting in both deep and surface nephrons.
为了确定近髓肾单位的滤过率是否受肾小管-肾小球反馈（TGF）调节，我们开发了两种适用于幼鼠乳头的微穿刺技术。一种技术是在髓袢降支（VDLH）中测量肾小管流量，同时以三种不同溶液以不同速率灌注髓袢升支（ALH）：改良林格液、人工髓袢溶液和含10⁻⁴M呋塞米的林格液。还在几个近髓肾单位中测量了单个肾单位肾小球滤过率（SNGFR）。另一种方案是测量髓袢降支中蜡块上游的肾小管停流压力（PSF）。在蜡块远端，通过ALH以不同速率灌注林格液。我们的结果首次证明了近髓肾单位存在TGF反应。在林格液灌注期间，VDLH和SNGFR降至零灌注时其值的42±4%和44±4%。使用髓袢溶液作为灌注液时观察到相同模式，而使用呋塞米时VDLH没有变化。PSF的最大降幅为14.1±1.4 mmHg。诱导PSF降幅达到最大值一半所需的灌注速率为9.1±0.9 nl/min。在这些大鼠的浅表肾单位近端小管中使用了类似的微穿刺技术，与深部肾单位相比，浅表肾单位的反馈反应较小。在两个肾单位群体中，该机制似乎在生理肾单位流速下都起作用。因此，TGF可通过作用于深部和浅表肾单位对整个肾脏的肾小球滤过率产生影响。
