Effect of indomethacin on papillary solute concentration in the potassium-deficient rat

Administration of indomethacin or meclofenamate to normal rats increases renal papillary solute concentration primarily by enhancing solute addition. A reduction in papillary solute concentration is characteristic of potassium deficiency. Of the multiple factors probably responsible for this reduction, several can be influenced by indomethacin or meclofenamate. The present study examined the effect of indomethacin on papillary solute concentration in the potassium-deficient rat. Indomethacin increased papillary solute concentration in normal but not potassium-deficient rats when studied in the conscious hydropenic state. Since indomethacin could increase papillary plasma flow in the potassium-deficient rat, potentially negating any enhancement of solute transport into the papilla, papillary plasma flow and papillary Cl concentration were determined in anesthetized surgically manipulated rats. Base-line papillary Cl concentrations were reduced in this setting. Indomethacin increased papillary plasma flow only in potassium-deficient rats but increased papillary Cl concentration equivalently in normal and potassium-deficient rats. The ability of indomethacin to increase papillary solute concentration in the potassium-deficient rat seemingly depends upon the experimental setting.