Hello everyone, So in renin angiotensin system, the NaCl concentration reaching the macula densa is monitored. Now my question if if there is loss of fluid from the body and both NaCl and water is lost from the body,plasma NaCl would be normal, now how would this affect macula densa. Okay so GFR decreases, but both NaCl and water filtration is decreased, so nacl reaching macula densa would be normal. I know I have really confused myself and I nedd some help. Thanks EDIT: Ok now I understand it is to do with glomerulotubular balance. But now I don't undertand that. Ok if there is high GFR, there is lots of proteins in peritubular capillary fluid and they can increase reabsorption of sodium. But sodium moves out tubular cells via active transport so how can this work? If there is decreased GFR how does glomerulotubular balance decrease sodium reabsorption?