The urinary excretion of purine derivatives in sheep is not influenced by long term treatment with vasopressin

Abstract

This study examines the influence of vasopressin (1-desamino-8-D-arginine vasopressin (dDAVP)) on the urinary excretion of purine derivatives in sheep. Subcutaneous injections of 12.5 μg of dDAVP given twice daily started 10 days before the measurements of renal functions. The urinary excretion of total purine derivatives was significantly lower in the dDAVP group (1.43±0.08 vs 2.18±0.18 μmol·min-1, P<0.01). Similar results were obtained for excretion of allantoin (0.90±0.07 vs 1.44±0.10 μmol·min-1, P<0.001), uric acid (0.30±0.02 vs 0.45±0.05 μmol·min-1, P<0.05) and xanthine (0.015±0.002 vs 0.008±0.002 μmol·min-1, P<0.05). The urinary excretion of hypoxanthine was unaffected by dDAVP administrations (0.22±0.01 vs 0.28±0.03 μmol·min-1, NS). The clearance protocol showed a decreased urine flow rate (1.40±0.12 vs 3.58±0.44 ml·min-1, P<0.001) without changes in glomerular filtration rate due to dDAVP. The urine urea concentration was significantly higher in the dDAVP group (18.71±1.49 vs 39.81±4.90 mmol·l-1, P<0.01). We conclude that vasopressin did not affect excretion of purine derivatives by the kidneys of sheep. The lower amount of total purine derivative excretion after treatment with vasopressin is a reflection of the urinary flow rate and water reabsorption.