The Seoul Journal of Medicine Vol. 29, No. 3:237- 243, September 1988 Effect of Higenamine on 3H-Norepinephrine Release In the Rabbit Pulmonary Artery1 2 Bong-Ae Wie*, Chan-Woong Park , Bong-Ki Kim, Jung-Kyoo Lim, Myung-suk Kim and Ho-Jin Myung* Department of Pharmacology and Neurology', College of Medicine, Seoul National Ilnroersitv. Seoul 11o 460, Korea = Abstract =It has been reported that higenamine increased the cardiac output and the heart rate and decreased the systemic vascular resistance and blood pressure by stimulating (3 -adrenoceptors. This study was undertaken to investigate the effects of higenamine on the pre- and post-synaptic adrenergic neurotransmission in the spiral strips of pulmonary arteries of New Zealand white rabbits. As the pre-synaptic response, the spontaneous and stimulation­ induced release of 3H-norepinephrine eH-NE), and as the post-synaptic response, the con­ tractile response were measured. The results were as follows: 1. Higenamine (3 X 10-6, 3 X 10-5 and 10-4M) increased both spontaneous and stimula­ tion-induced 3H-NE release dose-dependently, by 20-90% and 20-220%, respectively but decreased the contractile response in a dose-dependent manner. 2. The effect of higenamine in increase of spontaneous and stimulation-induced 3H-NE release was partially inhibited by the treatment of propranolol (3 X 10'--6M), but the effect 8 7 in contractile response was completely blocked. Isoproterenol (1.3 X 10- , 1.3 X 10- and 1.3 X 10-6M) had no effect on spontaneous and stimulation-induced 3H-NE release and contractile response. 3. The effect of higenamine was not inhibited by treatment with cocaine (3 X 10-5M). 8 7M) 4. The a z-adrenoceptor antagonist, yohimbine (3 X 10- and 3 X 10- increased the stimulation-induced 3H-NE release but did not affect spontaneous release. 5. Papaverine (3 X 10-6, 3 X 10-5 and 10-4M) increased spontaneous and stimualtion- induced 3H-NE release in a dose-dependent manner. These results sugest that higenamine increases neurotransmitter release by the mechanism of presynaptic action through the enhancement of cyclic AMP level in addition to stimulation of the presynaptic (3 -receptor and that the mechanism of post-synaptic action of higenamine lies in the stimulation of (3 -adrenoceptors. Key words: Higenamine, 13 -adrenoceptor, Presynaptic 3H-norepinephrine release, Vascular smooth muscle tuber which has long been used as a cardiac INTRODUCTION stimulant, a diuretic or an analgesic in Chinese Higenamine is an active component of Aconiti medicine. Park et al. (1984) have found that higenamine Increases the rate of tension de­ ReCl'lved 14/6/88: revised 16/8:88. acc:'ptcd 19/8/88 velopment and shortenes both the time to peak I This work was partly supproted by '88 SNlI Daewoo tension and the total duration of contraction in a J\esearch Fund. dose-dependent manner. These effects of hige­ ~ Author for correspondence namine were competitively blocked by proprano- .