RELAXATION EFFECT OF BOVINE PARATHYROID-HORMONE 1-34 ON RABBIT AORTA

Bovine parathyroid hormone 1-34 (bPTH1-34) was studied in rabbit isolated aortic strips. It was found that bPTH1-34 lowered the basal tension of the aortic strips (IC50 48 .mu.mol/L). Like nifedipine and verapamil, bPTH1-34 inhibited the contraction induced by BAY k 8644 (1.4 .mu.mol/L) with an IC50 value of 0.95 .mu.mol/L. In contrast, its inhibition of contraction induced by norepinephrine was weak. It is suggested that bPTH1-34 reduces the tension in vascular smooth muscle by acting mainly on potential sensitive calcium channels to decrease calcium transmembrane influx.