Serotonin formation in nonblood-perfused rat kidneys.
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.
D006916:5-Hydroxytryptophan / Q000378:metabolism; D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism; D002230:Carbidopa / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D012082:Renal Veins / Q000187:drug effects; D012701:Serotonin / Q000096:biosynthesis*; D014655:Vascular Resistance / Q000187:drug effects
D012701:Serotonin; D006916:5-Hydroxytryptophan; D001142:Aromatic-L-Amino-Acid Decarboxylases; D002230:Carbidopa