Nonsteroidal anti-inflammatory drugs alter vasa recta diameter via pericytes

Abstract

We have previously shown that vasa recta pericytes are known to dilate vasa recta capillaries in the presence of PGE ₂ and contract vasa recta capillaries when endogenous production of PGE ₂ is inhibited by the nonselective nonsteroidal anti-inflammatory drug (NSAID) indomethacin. In the present study, we used a live rat kidney slice model to build on these initial observations and provide novel data that demonstrate that nonselective, cyclooxygenase-1-selective, and cyclooxygenase -2-selective NSAIDs act via medullary pericytes to elicit a reduction of vasa recta diameter. Real-time images of in situ vasa recta were recorded, and vasa recta diameters at pericyte and nonpericyte sites were measured offline. PGE ₂ and epoprostenol (a prostacyclin analog) evoked dilation of vasa recta specifically at pericyte sites, and PGE ₂ significantly attenuated pericyte-mediated constriction of vasa recta evoked by both endothelin-1 and ANG II. NSAIDs (indomethacin > SC-560 > celecoxib > meloxicam) evoked significantly greater constriction of vasa recta capillaries at pericyte sites than at nonpericyte sites, and indomethacin significantly attenuated the pericyte-mediated vasodilation of vasa recta evoked by PGE ₂, epoprostenol, bradykinin, and S-nitroso- N-acetyl-l-penicillamine. Moreover, a reduction in PGE ₂ was measured using an enzyme immune assay after superfusion of kidney slices with indomethacin. In addition, immunohistochemical techiques were used to demonstrate the population of EP receptors in the medulla. Collectively, these data demonstrate that pericytes are sensitive to changes in PGE ₂ concentration and may serve as the primary mechanism underlying NSAID-associated renal injury and/or further compound-associated tubular damage.