Tucker B J, Blantz R C
Am J Physiol. 1978 Aug;235(2):F142-50. doi: 10.1152/ajprenal.1978.235.2.F142.
The determinants of absolute proximal reabsorption (APR) were studied in four groups of rats during hydropenia, partial renal vein occlusion (RVO), saline expansion, and RVO after saline expansion. Nephron filtration rate (SNGFR), nephron plasma flow (RPF), APR, and proximal tubule (Pt) peritubular capillary (HPc), and interstitial (HPi) hydrostatic pressures were measured by micropuncture techniques. Subcapsular space (pii) and star peritubular capillary (piE) oncotic pressures were also determined. The peritubular capillary permeability coefficiency (LpAR) and the corresponding effective reabsorptive pressure (ERP) were computed, where APR = LpAR . ERP, and ERP = net reabsorptive pressure across the peritubular capillary. The results indicate that APR correlates best with SNGFR (P less than 0.05), but not with (pii - HPi), RPF, or LpAR. There was a significant relationship between piE and LpAR, where LpAR fell with increases in piE (P less than 0.01). In conclusion, 1) changes in absolute proximal reabsorption correlate best with changes in nephron filtration rate but not with (pii - HPi) across this range of values, 2) changes in efferent oncotic pressure (piiE) correlated inversely with LpAR, and 3) glomerulotubular balance in the proximal tubule can be partially attributed to intraluminal factors.
在禁水、部分肾静脉阻塞（RVO）、盐水扩容以及盐水扩容后RVO这四种情况下，对四组大鼠的绝对近端重吸收（APR）的决定因素进行了研究。通过微穿刺技术测量了肾单位滤过率（SNGFR）、肾单位血浆流量（RPF）、APR、近端小管（Pt）周围毛细血管（HPc）以及间质（HPi）的静水压。还测定了被膜下间隙（pii）和星状周围毛细血管（piE）的胶体渗透压。计算了肾小管周围毛细血管通透性系数（LpAR）和相应的有效重吸收压力（ERP），其中APR = LpAR·ERP，且ERP = 跨肾小管周围毛细血管的净重吸收压力。结果表明，APR与SNGFR的相关性最佳（P < 0.05），但与（pii - HPi））、RPF或LpAR无关。piE与LpAR之间存在显著关系，其中LpAR随piE的增加而下降（P < 0.01）。总之，1）在这个值范围内，绝对近端重吸收的变化与肾单位滤过率的变化相关性最佳，而与（pii - HPi）无关；2）出球小动脉胶体渗透压（piiE）的变化与LpAR呈负相关；3）近端小管的球管平衡可部分归因于管腔内因素。
