PTH2 and PTH1 Receptor Ligands
Parathyroid hormone receptors found on osteoblasts in bone and renal tubule cells in kidney elevate blood calcium levels when stimulated by parathyroid hormone (PTH) and PTH-related protein (PTHrP). Excessive secretion of PTH from the parathyroid gland results in primary hyperparathyroidism. Production of PTHrP by various tumors results in humoral hypercalcemia of malignancy. In both of these conditions, excessive blood calcium levels lead to clinically significant morbidity. A parathyroid hormone antagonist could therefore have therapeutic value.