Pharmacological characteristics of higenamine on adrenergic β-receptors

아드레날린성 β-수용체에 대한 higemamine의 약리학적 특성

Higenamine is an Aconiti tuber derived compound whose chemical structure is 1-(4'-hydroxybenzyl)-6, 7-dihydroxy-1, 2, 3, 4-tetrahydroisoquinoline containing catechol ring and tetrahydroisoquinoline nucleus in its own structure, both of which are well known to have agonistic effects on adrenergic receptors. Using guinea-pig atria(rich in ${\beta}_1$-receptor) and treachea(rich in ${\beta}_2$-receptor), we studied pharmacological actions of higenamine on these organs with special interest of its relevancy of ${\beta}$-receptor selectivity. In order to further clarify its pharmacological characteristics, the influncences of pretreatment of reserpine or cocaine were also investigated. The results were summarized as follows : 1. Higenamine had remarkable chronotropic, inotropic and bronchodilator effects in guinea-pig spontaneously beating right atria, left atria and trachea, in dose-dependent manners. 2. All of above actions were blocked competitively by propranolol, which shows nonselectivity of higenamine on ${\beta}$-receptor. $pA_2$ values of propranolol against higenamine were 7.93, 7.76 and 8.46 in guinea-pig right atria, left atria and treachea, respectively. 3. Reserpine pretreatment(5mg/kg, ip, 24h) did not show my decrease in pharmacological actions of higenamine, which suggests higenamine has direct action on ${\beta}$-receptor not via catecholamine release. 4. Cocaine pretreatment$(1{\mu}M)$ had no influence on pharmacological actions of higenamine in contrast with nor epinephrine, which suggests there is no neuronal uptake mechanism of higenamine in the studied organ preparations.