Renal Action of Parathyroid Extract in the Chicken

The renal action of parathyroid extract has been studied in the chicken, in which a renal portal system facilitates separation of renal tubular from systemic and glomerular effects. It was found that net secretion of phosphate occurs in the chicken kidney both at endogenous plasma phosphate levels and during the infusion of phosphate. The rate of secretion seems to be independent of the plasma phosphate concentration. Infusion of parathyroid extract into one renal portal system results in a unilateral increase in phosphate excretion. In some experiments unilateral net secretion of phosphate occurred. No consistent changes in glomerular filtration rate or plasma phosphate concentration occur when parathyroid extract is administered. These results indicate that parathyroid extract has a direct action on the renal tubule in the chicken.