Cardiovascular actions of the essential oil of Rhododendron anthopogonoides

A study on the pharmacologic effects of essential oil of R. anthopogonoides(EORA) on the cardiovasvular system revealed that 1. EORA produced a decrease of the cardiac contractility and heart rate in anesthetized rats and isolated hearts of rats. 2. The iv drip of EORA 504±8 mg/kg led to the death of anesthetized rats and ECGpatterns showed lengthening of the intervals of P-R, Q-T and QRS complex. The different routes of administration of EORA at small daily doses for a few days did not produce a noticeable influence on the ECG of conscious rats and rabbits except a slowing of the heart rate. 3. Intravenous injections of pituitrin inducded a heightened T wave. This could be prevented by a pretreatment with iv EORA 80 mg/kg in rabbits or ip EORA 89 mg/kg/day for 13 days in rats. An ip or po administration of EORA elevated significantly the tolerance toward the acute hypoxia when the mice and rats were exposed to a reduced atmospheric pressure. 4. In anesthetized dogs, EORA caused a decrease of the internal carotid vascular resistance, so the blood flows were markedly increased. 5. An iv injection of EORA 50 or 80 mg/kg produced a prompt and remarkable fall of the arterial blood pressure in anesthetized rabbits. The acute hypotensive action of EORA is chiefly due to its direct inhibitory effect on the cardiac activities and its vasodilatation.