Romano G, Favret G, Damato R, Bartoli E
Department of Internal Medicine, University of Udine, Medical School, Italy.
Exp Physiol. 1998 Jan;83(1):35-48. doi: 10.1113/expphysiol.1998.sp004090.
The relative contribution of intraluminal versus peritubular factors in mediating glomerulo-tubular balance (GTB) is still controversial. We modulated the load of tubular fluid to the proximal tubule of single nephrons of rats by injecting oil into the efferent arteries (EAO). In fifty nephrons the changes in reabsorption induced by obstruction occurred in the same direction as, and were significantly correlated with, the simultaneous changes in single nephron glomerular filtration rate (SNGFR) (y = -0.54 + 0.92x, R = 0.91, P < 0.0001). In an additional set of thirty-nine nephrons the load of tubular fluid was changed, during EAO, by partial collection from Bowman's space or from the early proximal convolution. Thus, the rate of tubular fluid delivery along the proximal tubule was changed in an experimental situation that prevented any modification in the oncotic pressure of peritubular capillaries. The changes in proximal deliveries during this experimental condition were significantly correlated with those during reabsorption (y = -2.87 + 0.71x, R = 0.82, P < 0.0001). These data demonstrate that GTB is fully expressed even when the native peritubular environment is kept constant while the rate of perfusion of proximal tubular segments with native tubular fluid is changed.
管腔内因素与肾小管周围因素在介导肾小球-肾小管平衡（GTB）中的相对作用仍存在争议。我们通过向大鼠单个肾单位的出球小动脉注射油（EAO）来调节近端小管的肾小管液负荷。在50个肾单位中，梗阻引起的重吸收变化与单个肾单位肾小球滤过率（SNGFR）的同时变化方向相同，且显著相关（y = -0.54 + 0.92x，R = 0.91，P < 0.0001）。在另外39个肾单位中，在EAO期间，通过从鲍曼囊或近端曲部早期部分收集来改变肾小管液负荷。因此，在防止肾小管周围毛细血管胶体渗透压发生任何改变的实验情况下，沿近端小管的肾小管液输送速率发生了变化。在这种实验条件下近端输送的变化与重吸收期间的变化显著相关（y = -2.87 + 0.71x，R = 0.82，P < 0.0001）。这些数据表明，即使在肾小管周围的天然环境保持恒定而用天然肾小管液灌注近端小管节段的速率发生变化时，GTB仍能充分表现出来。
