Figure 125

A-C, Synergistic effects of angiotensin II on proximal reabsorption and tubuloglomerular feedback mechanisms. The actions of angiotensin II on proximal nephron reabsorption and the ability of angiotensin II to enhance the sensitivity of the tubuloglomerular feedback (TGF) mechanism prevent a compensatory increase in glomerular filtration rate caused by the reduced distal tubular flow. These actions allow elevated angiotensin II levels to exert a sustained reduction in sodium delivery to the distal nephron segment. This effect is shown here by the shift of operating levels to a lower proximal fluid flow under the influence of elevated angiotensin II [27]. The effects of angiotensin II to enhance TGF sensitivity allow the glomerular pressure (GP) and nephron filtration rate to be maintained at a reduced distal volume delivery rate that would occur as a consequence of the angiotensin II effects on reabsorption. SNGFR—single nephron glomerular filtration rate. (Panels B and C adapted from Mitchell et al. [27].)

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