Action of fragments of human parathyroid hormone on blood pressure in rats.

Abstract

To investigate localization of the action on blood pressure in the peptide chain of parathyroid hormone (PTH), the effect of 7 fragments of human(h)PTH-(1-34) fragments was determined on blood pressure in anesthetized rats. hPTH-(1-7) and -(28-34) fragments had no effect up to 1 .times. 10-6 mol/kg. hPTH-(8-34), -(13-34), -(18-34), and -(23-34) fragments showed significant hypotensive activity. The decrease in the chain length lowered the hypotensive activity. Some amino acids in position 23-34 appear to be necessary for the hypotensive activity. This accords with the previous report suggesting that 5 amino acids in position 24-28 are essential. hPTH-(8-34) and -(13-34) fragments showed initial transient hypertensive activities. hPTH-(1-34) fragment had only hypertensive action, suggesting that some amino acids in position 8-13 are necessary for hypertensive activity.