FEEDBACK-CONTROL OF GLOMERULAR BLOOD-FLOW, PRESSURE, AND FILTRATION-RATE

Definition of the pressure and permeability determinants of GFR does not explain the way in which the values of glomerular plasma flow and hydraulic pressure are controlled by mechanisms that regulate GFR. Controlling mechanisms that have been considered capable of influencing GFR include hormonal systems (both systemic and local); neural activity; pressure- or stretch-responsive elements intrinsic to vascular smooth muscle; variations in the rate of fluid reabsorption by renal tubules; and a feedback pathway involving an afferent limb through the loop of Henle to the distal tubule, a sensing mechanism in the distal tubule, and efferent limb external to the tubule system, and an effector mechanism in the glomerular resistance vessels. This feedback pathway is the concern of this review.