Peripheral metabolism of bovine parathyroid hormone in the dog

Four dogs were infused with highly purified bovine parathyroid hormone until constant levels of immunoreactive hormone were attained in the circulation. Simultaneous samples of plasma were then obtained from the aorta, from hepatic, renal, and femoral veins, and later from a pulmonary artery and the left ventricle. Radioimmunoassay of these samples revealed mean arteriovenous differences of -23% across the liver and -19% across the kidney. No significant differences were found across the lung or lower extremity. After termination of the infusion the disappearance rate of immunoreactive hormone in external jugular-venous blood was multiexponential: the predominant initial T 1/2 was 4, 6, and 8 min, and the terminal component was 60, 54, and 99 min. respectively, in 3 dogs.