Chronotropic actions of bPTH-(1-34) in the right atrium of the rat

Bovine parathyroid hormone and its N-terminal (1-34) peptide fragment (bPTH-(1-34] are known to possess direct hypotensive activity in the rat. The purpose of the present study was to determine if bPTH-(1-34) possessed a direct chronotropic action as well. In vivo studies revealed that bPTH-(1-34) d...

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Bibliographic Details
Published inCanadian journal of physiology and pharmacology Vol. 61; no. 10; p. 1162
Main Authors Tenner, Jr, T E, Ramanadham, S, Yang, M C, Pang, P K
Format Journal Article
LanguageEnglish
Published Canada 01.10.1983
Subjects
Adrenergic Fibers - physiology
Animals
Cyclic AMP - physiology
Heart - drug effects
Heart Rate - drug effects
Isoproterenol - pharmacology
Male
Parathyroid Hormone - antagonists & inhibitors
Parathyroid Hormone - pharmacology
Propranolol - pharmacology
Rats
Reserpine - pharmacology
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Summary:Bovine parathyroid hormone and its N-terminal (1-34) peptide fragment (bPTH-(1-34] are known to possess direct hypotensive activity in the rat. The purpose of the present study was to determine if bPTH-(1-34) possessed a direct chronotropic action as well. In vivo studies revealed that bPTH-(1-34) did produce a chronotropic effect in the rat comprising both a direct component as well as a reflex tachycardia related to its hypotensive actions. In vitro studies of isolated right atria indicated that while bPTH-(1-34) had no positive inotropic effect, it did produce significant chronotropic effects which were direct and dose-dependent. The potency of bPTH-(1-34) was found to be similar to that of isoproterenol, however, it was only one-third as effective as isoproterenol in maximally increasing atrial rate. A slight but significant increase in atrial cyclic AMP was generated prior to the chronotropic actions of bPTH-(1-34).
ISSN:0008-4212
DOI:10.1139/y83-173