Participation of the kidney in the kinetics of arginine vasopressin in the water-loaded rat.
The kidney is a target organ for antidiuretic hormone (ADH) and it is also the main organ involved in the clearance of this hormone. There is controversy on the mechanisms involved in the renal handling of ADH, mainly in regard to whether it is secreted or reabsorbed. Kinetic and renal clearance studies of ADH were performed in water-loaded rats and were compared with inulin (glomerular filtration marker) and tetraethylammonium (TEA, marker of organic cation secretion). The kinetics of the three molecules fitted a bicompartmental model. Distribution constants of [125I]-ADH were twofold higher than those of inulin. Elimination constant was higher for inulin than for ADH (0.049 +/- 0.001 vs. 0.020 +/- 0.003 min-1, respectively), suggesting reabsorption of the hormone. The ratios of Clearance ADH/Clearanceinulin and ClearanceTEA/Clearanceinulin were 0.14 and 4.86, respectively. In summary, data from kinetic studies and from renal clearances suggested that ADH is reabsorbed.
Mendoza
M E
ME
Physiology and Biophysics Department, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, México, D.F.
Namorado
M C
MC
Reyes
J L
JL
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D004326:Drinking; D007444:Inulin / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D007668:Kidney / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D014867:Water / Q000378:metabolism
D013757:Tetraethylammonium Compounds; D014867:Water; D001127:Arginine Vasopressin; D019789:Tetraethylammonium; D007444:Inulin