title: Sites of clearance of endogenous parathyroid hormone in the vitamin D-deficient dog.
abstract: The sites of clearance of endogenous parathyroid hormone (PTH) were studied in dogs who developed secondary hyperparathyroidism on a vitamin D-deficient diet. Simultaneous blood samples were obtained from the femoral artery, and the hepatic, renal, portal, and femoral veins. Radioimmunoassay of canine immunoreactive PTH (iPTH) in a heterologous bovine PTH (bPTH) system indicated that the kidney and liver extracted 49% and 46%, respectively, of the iPTH circulating through these organs. Characterization of the circulating iPTH in these animals was carried out by gel filtration and radioimmunoassay of the eluant fractions utilizing specific amino- and carboxyl-terminal antisera. The hormone in the peripheral circulation co-eluted with [125I]-iodobPTH and no fragments of iPTH were detected. Immunochemical differences between bovine and canine PTH were detected in the carboxyl-terminal region of the molecule. The results indicate that endogenous PTH in the vitamin D-deficient, hypocalcemic dog is cleared by the kidney and liver and that the predominant form of the hormone in this animal is similar to glandular bPTH 1-84.
mesh_terms: D000818:Animals; D002417:Cattle; D004285:Dogs; D006962:Hyperparathyroidism, Secondary / Q000209:etiology; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D010281:Parathyroid Hormone / Q000276:immunology / Q000378:metabolism*; D011863:Radioimmunoassay; D014808:Vitamin D Deficiency / Q000150:complications / Q000378:metabolism*
chemical_list: D010281:Parathyroid Hormone