TY - JOUR T1 - Serotonin formation in nonblood-perfused rat kidneys. JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 53 LP - 56 VL - 228 IS - 1 AU - C T Stier, Jr AU - G McKendall AU - H D Itskovitz Y1 - 1984/01/01 UR - http://jpet.aspetjournals.org/content/228/1/53.abstract N2 - Infusion of the aromatic L-amino acid decarboxylase substrate L-5-hydroxytryptophan (L-5-HTP) at 1.5, 3.0 and 15 micrograms/min into isolated Krebs-Henseleit-perfused rat kidneys was associated with serotonin output in the urinary and venous effluents. Serotonin was measured by high-performance liquid chromatography using electrochemical detection. Infusion at the two higher doses of L-5-HTP caused marked increases in renal vascular resistance (RVR) of over 80 and 490%, respectively. Administration of the aromatic L-amino acid decarboxylase inhibitor carbidopa (20 micrograms) decreased serotonin output and RVR to base-line levels despite continued infusion of L-5-HTP. Infusion of the D-isomer of 5-HTP at 3 micrograms/min did not significantly alter RVR and produced minimal increases in serotonin output relative to L-5-HTP. These results are consistent with the stereospecific formation of serotonin from its amino acid precursor 5-HTP by whole rat kidney. ER -