Difference in Renal Tubular Transport Effects of 1–34 and 1–84 Parathyroid Hormone (PTH)

Abstract

It has recently been established that the fragment of parathyroid hormone (PTH) consisting of the first 34 amino acids at the amino terminus possesses biological activity similar to that demonstrated by the native, 1–84 hormone molecule. In particular, the 1–34 fragment has been shown to be capable of inducing hypercalcemia and phosphaturia in vivo, and can stimulate the adenylate cyclase system in vitro.^1–3 The characteristic acute effects of PTH on the kidney are the production of a marked phosphaturia associated with either a decline or no change in calcium excretion.⁴ Although data detailing the effects of 1–34 PTH on phosphate excretion are available in the literature, the effect of the fragment on calcium transport has not been studied. We therefore compared the action of 1–34 and 1–84 PTH on calcium excretion in acute clearance studies performed in the dog.