Cardiovascular effects of bPTH-(1-34) and isoproterenol in the frog, Rana tigrina.
1. The cardiovascular effects of bovine parathyroid hormone fragment [bPTH-(1-34)] and isoproterenol (ISO) on frog (Rana tigrina) isolated atria and helical strips of blood vessels were examined since PTH produces a beta-adrenergic-like effect in the mammal. 2. Data showed that both bPTH-(1-34) and ISO were vasorelaxant in KCl and arginine vasoctocin (AVT) preconstricted dorsal aorta, iliac and femoral arteries. 3. They both relaxed extracellular calcium-dependent contrations. 4. There was no additive nor synergistic effect between them in AVT preconstricted strips. 5. Both bPTH-(1-34) and ISO were positively inotropic but differed in their chronotropic effects, being negative and positive. 6. In the tiger frog, bPTH-(1-34) shows beta-adrenergic like contractile responses in both the cardiac and vascular smooth muscle as in the mammal, but not in the heart rate.
Chiu
K W
KW
Department of Biology, University of Hong Kong.
Chung
T Y
TY
Pang
P K
PK
D000818:Animals; D002319:Cardiovascular System / Q000187:drug effects*; D003864:Depression, Chemical; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006728:Hormones / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D011898:Ranidae / Q000502:physiology*; D013268:Stimulation, Chemical
D006728:Hormones; D010281:Parathyroid Hormone; D010446:Peptide Fragments; C025076:parathyroid hormone (1-34), bovine; D007545:Isoproterenol