The effect of indomethacin on the ultrastructure of renomedullary interstitial cells of the rat.

The administration of the prostaglandin synthetase inhibitor indomethacin to the rat result in a significant increase of the number as well as the size and density of the lipid granules of renomedullary interstitial cells. The increased granularity is associated with the ultrastructural alterations of the organelles which are characteristic for cells with small secretory activity (a sparse rough and smooth endoplasmic reticulum and a small GOLGI complex). The findings indicate that there exists an inverse correlation between the number of the lipid granules of the interstitial cells and the secretory activity of these cells and seem to support the hypothesis that the interstitial cell lipid granules serve as storage site for renal prostaglandin precursors.