Peritubular and intraluminal concentrations of diuretics effecting isotonic fluid absorption in the kidney tubule.

Abstract

In micropuncture studies the isotonic fluid absorption from the proximal convolution of the rat kidney was measured while simultaneously perfusing the peritubular blood capillaries. Diuretics were added either to the intraluminally injected fluid or the capillary perfusate. When applied peritubularly, all diuretics caused a strong inhibition of the isotonic fluid absorption. 15 % inhibition was reached in the concentration range 2–5 x 10–7M and 50% inhibition from 3 x 10–5 to 4 x 10–4M. The diuretics were also effective when applied intraluminally, although 100 times higher concentrations (1.5–6 x 10–5 M)were necessary to produce 15 % inhibition.