Essential fatty acid-supplemented diet decreases renal excretion of immunoreactive arginine-vasopressin in essential fatty acid-deficient rats.

Essential fatty acid (EFA)-deficient rats have been reported to have very concentrated urine and low urinary prostaglandin E2 (PGE2) excretion. Both parameters were normalized by feeding an EFA-supplemented diet (H.S. Hansen [1981] Lipids 16, 849-854). The urinary excretion rate of immunoreactive-arginine-vasopressin (iAVP) has been determined in these rats. The iAVP excretion rate was high: ca. 4.8 mU/24 hr, during the EFA-deficient period compared to the controls, 0.7-1.3 mU/24 hr. One day after the dietary change, iAVP excretion rate was still high, but it decreased significantly (p less than 0.05) at the second measurement 7 days later. It is suggested that the water-conserving effect of vasopressin 1 day after the dietary change was suppressed by the very high PGE2 production, resulting in normal renal water excretion. PGE2 and water excretion data were published in the paper just cited.