Higenamine is an Amniti 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 ¥â©û-receptor) and treachea(rich in /¥â©ü-receptor), we studied pharmacological actions of higenamine on these organs with special interest of its relevancy of ¥â-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 propianolol, which shows nonselectivity of higenamine on (¥â-receptors. pA©üpropranolol against higenamine were 7.93, 7.76 and 8.46 in guinea-pig right atria, left atria and treachea, respectively.
3. Reserpine pretreatment(5§·/§¸, ip, 24h) did not show my decrease in pharmacological actions of higenamine, which suggests higenamine has direct action on ¥â-receptor not via catecholamine release.
4. Cocaine pretreatment(1¥ìM) 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.
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