Effect of Chronic Alterations in Sodium Intake on Prostaglandin Release from Isolated Perfused Rabbit Kidney

Bioassayable PGE² like material released from isolated perfused rabbit kidneys was assayed in superfusion cascade, and the response to bradykinin and angiotensin II quantitated in a dose-dependent manner. Chronic high-sodium intakes produced qualitatively and quantitatively similar responses compared to normal diets when kidneys were stimulated with BK or A¹¹. Low Na⁺ diets increased sensitivity to BK or A¹¹ with a shift of the dose —response curves (DRC) to the left with the same maximum response. No difference in in vitro metabolism of [¹⁴C]arachidonic acid by microsomal preparations of cortex and medulla from Na+-loaded and Na+-depleted rabbits could be detected. These results suggest that the shift of the DRC to the left for angiotensin II and BK may be related to increased sensitivity for arachidonic acid release in response to the peptides and may be responsible for the observed increase in PGE² urinary excretion observed in chronic salt depletion in rabbits.