Hypotensive action of parathyroid hormone preparations on rats and dogs.

Abstract

Bovine parathyroid extract and 2 commercial preparations containing the first 34 amino acids of synthetic bovine parathyroid hormone [bPTH-(1-34)] produced dose-related hypotension in anesthetized rats. Dogs were 10 times more sensitive to the 2 bPTH-(1-34) preparations than were rats. Propranolol, phentolamine, atropine and promethazine did not affect the hypotensive action of bPTH-(1-34) in rats and dogs. bPTH-(1-34) decreased perfusion pressure in rat hindlimbs perfused in situ with Ringer''s solution and was a vasodilator in dog kidneys perfused in vitro with Ringer''s solution. Helical strips of rabbit aorta were also relaxed by bPTH-(1-34). Apparently, the direct vasodilatory action of bPTH preparations represents an intrinsic property of parathyroid hormone and the hypotensive effect of this hormone is produced by part or all of the first NH2-terminal 34 amino acids.