Pressure inside the nephron Dialysis The net filtration pressure in glomerular capsule is: 55 – (30 + 15) = 10 mmHg. By this net pressure the kidneys will filter around 125 ml per min, this called glomerular filtration rate (GFR Any factor affect net filtration pressure will cause alteration in GFR The main factor may cause this alteration is the systemic blood pressure Usually the kidneys maintain renal blood flow by a mechanism called autoregulation whereby Renal blood flow is maintained at a constant pressure across a wide range of systolic blood pressures (from 80 to 200 mmHg). In severe shock when the systolic blood pressure falls below 80 mmHg, autoregulation fails and renal blood flow and the hydrostatic pressure decrease, impairing filtration within the nephrons