Pinnick R V, Savin V J
Am J Physiol. 1986 Jan;250(1 Pt 2):F86-91. doi: 10.1152/ajprenal.1986.250.1.F86.
We measured glomerular ultrafiltration coefficient (Kf) of isolated superficial (S) and deep (D) glomeruli of normovolemic and volume-depleted rats. Filtration was induced in vitro, and Kf was calculated from the maximum rate of change in glomerular size. Basement membrane area (A) for each glomerulus was estimated from morphometric analyses, and glomerular capillary hydraulic conductivity (Lp) was calculated by the formula Lp = Kf/A. Kf of S and D glomeruli of normovolemic rats were 2.98 +/- 0.98 and 4.25 +/- 0.07 nl . min-1 . mmHg-1, respectively. In hypovolemic rats, Kf of S glomeruli fell by approximately 50% to 1.52 +/- 0.14 nl . min-1 . mmHg-1 (P less than 0.001), whereas Kf of D glomeruli remained unchanged at 4.28 +/- 0.10 nl . min-1 . mmHg-1. Lp, calculated using the peripheral capillary area, averaged 1.98 +/- 0.09 and 1.98 +/- 0.06 microliter . min-1 . mmHg-1 . cm-2 in S and D glomeruli of normovolemic rats and 1.89 +/- 0.11 microliter . min-1 . mmHg-1 . cm-2 in D glomeruli of hypovolemic rats. Lp of S glomeruli of volume-depleted rats (0.90 +/- 0.03 microliter . min-1 . mmHg-1 . cm-2) was lower than in any of the other three samples. Mild hypovolemia causes the Kf of S glomeruli to decline, whereas Kf of D glomeruli remains constant. The decrease in Kf occurs without an alteration in capillary area and is most likely due to a decrease in Lp.
我们测量了正常血容量和血容量减少大鼠的孤立浅表（S）和深部（D）肾小球的肾小球超滤系数（Kf）。在体外诱导滤过，并根据肾小球大小的最大变化率计算Kf。通过形态计量分析估算每个肾小球的基底膜面积（A），并通过公式Lp = Kf/A计算肾小球毛细血管水力传导率（Lp）。正常血容量大鼠S和D肾小球的Kf分别为2.98±0.98和4.25±0.07 nl·min-1·mmHg-1。在血容量不足的大鼠中，S肾小球的Kf下降约50%，至1.52±0.14 nl·min-1·mmHg-1（P<0.001），而D肾小球的Kf保持不变，为4.28±0.10 nl·min-1·mmHg-1。使用外周毛细血管面积计算的Lp，在正常血容量大鼠的S和D肾小球中平均分别为1.98±0.09和1.98±0.06微升·min-1·mmHg-1·cm-2，在血容量不足大鼠的D肾小球中为1.89±0.11微升·min-1·mmHg-1·cm-2。血容量减少大鼠的S肾小球的Lp（0.90±0.03微升·min-1·mmHg-1·cm-2）低于其他三个样本中的任何一个。轻度血容量不足导致S肾小球的Kf下降，而D肾小球的Kf保持恒定。Kf的降低在毛细血管面积无改变的情况下发生，最可能是由于Lp降低所致。
