Renal Handling of 5-Hydroxyindoleacetic Acid in the Dog. ∗

Summary

The renal clearance of 5-HIAA at low plasma concentrations in the dog averaged 143 ± 7.8 ml/min/M² with simultaneous creatinine and sodium iodohippurate I₁₃₁ clearances of 66 ± 3.6 and 223 ± 20 ml/min/M², respectively. Probenecid administration resulted in a marked depression of the 5-HIAA clearance. Tubular secretion accounted for 88% of the 5-HIAA excreted in the urine. A tubular maximum was achieved at plasma 5-HIAA levels above 34 mg%. Ultrafiltration studies demonstrated that 80 to 87% of the plasma 5-HIAA was bound to proteins with the major portion bound to albumin.