Lysophospholipids are natriuretic and diuretic in rats

The effects of lysophosphatidylcholine (LPC) and some of its analogues on renal sodium (UNaV) and water excretion (V) were examined in the pentobarbital sodium-anesthetized rat. LPC caused the increase in UNaV and V with a steep dose response. The natriuretic effect began within 20 min after a bolus injection and lasted for 7 h. The natriuresis and diuresis were not affected when the phospholipid was given as an LPC-albumin complex. Natriuretic activity was eliminated by substituting unsaturated bonds in the 1-acyl group and by removing the choline group on position 3. Natriuretic activity was not affected by substitution of 1-alkyl for 1-acyl groups and was stereospecific. These results demonstrate a unique, previously unrecognized effect of lysophospholipids and suggest that they may account for some of the previously demonstrated natriuretic activity of plasma.