1. The production of prostaglandin (PG) E2, F2α and thromboxane B2 (TXB2) by isolated glomeruli, cortical tubular suspensions and medullary and papillary slices was measured in normal Long–Evans rats 4, 8 and 14 days after starting on oral Na+ load and the results were compared with those of rats on a normal Na+ intake.
2. In glomeruli, PGE2 decreased at days 4 and 8, and returned to normal at 14 days. PGF2α decreased only at day 4 and TXB2 decreased in all Na+-loaded animals. In cortical suspensions, a transient decrease of PGE2 was observed at day 4. In medullary slices, PGE2 and TXB2 decreased in all experimental periods. In contrast, in papillae, a significant increase of PGE2 was observed with Na+ loading at day 8, but PGF2α and TXB2 did not change consistently.
3. Similar changes were observed in rats with hypothalamic diabetes insipidus (DI rats) Na+ loaded for 4 days, as compared with DI rats on a normal Na+ intake.
4. The results suggest that prostanoids participate in the renal adaptation to an increased Na+ intake, and that this response is relatively independent of the presence of antidiuretic hormone.