Substance P decreases fluid absorption in the renal proximal tubule

The activity of substance P (SP) on proximal tubule transport was analyzed in isolated rabbit perfused proximal tubules. Systemic infusion of SP on isolated rabbit proximal tubules inhibited fluid absorption at lower concentrations. The effects of SP on the rates of fluid reabsorption after partial ureteric blockade were also initiated by a very complex cascade of events that increased urine flow rates. Furthermore, the activity of SP on proximal absorption was not affected by NO inhibition.