The pharmacological effects of synthetic butylidenephthalide (Bdph), the most potent antispasmodic agent found in the neutral oil of Ligusticum wallichii Franch., were examined in this study. In vivo, Bdph exerted a significant antihypertensive effect in anaesthetized renal hypertensive rats at a dose of 30 mg/kg (i.v. or i.p.), or 60 mg/kg (p.o.). Bdph antagonized noradrenaline (NA) induced increases in blood pressure in anaesthetized normotensive rats. In addition, Bdph prevented the pituitrin-induced T-wave lowering of the ECG in anaesthetized rats. It also dose-dependently decreased coronary arterial pressure in dogs. It is concluded that Bdph dilates coronary vessels. In vitro, Bdph non-competitively antagonized adrenaline-induced contraction in isolated rabbit aortic strips. It also significantly antagonized the NA-induced maximum decrease in perfusion rate of isolated rabbit ears. However, the vasodilator effect may cause a heat loss because Bdph significantly lowered the rectal temperature of rats at ambient temperature of 20°C, but not at 30°C. Bdph might be a useful coronary dilator and antihypertensive drug.
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