Zur Wirkung pflanzlicher Glykoside auf Widerstandsgefäße und Kapazitätsgefäße
Journal/Book: Arzneimittelforschung. 1984; 34: 423-429.
Abstract: In the anaesthetized cat, SCOA (Miroton?), a product which contains extracts from Scilla. Convallaria. Oleander and Adonis, displays not only its well-known positive inotropic effect but has also constrictor effects an veins it-hen applied in intravenous doses of 2l.5-100 GPU/kg (GPU = guinea-pig units, i.e. cardiotoxic equivalents related to 1 g body weight of guinea-pigs). The latter effect differs in that it is somewhat more prolonged. With intraduodenal administration the doses required to achieve equal peak effects as with intravenous injection are about 4 times larger and this suggests a relatively good enteral availability in the cat. SCOR constricts not only veins but also arteries. However, this latter effect is comparatively small and occurs only after intraarterial Infusion of high doses (9.1 and 91 GPU/min, respectively). The cardiac glycosides contained in the drug product primarily account for its vasoactive qualities. The venous constrictor effect correlates with the guinea-pig units. In qualitative respects, the pure glycosides cymarin, convallatoxin, proscillaridin, and scillaren exert equal effects. There is, however, evidence that the correlation between the effect an veins and an the heart differs for the glycosides tested. Based an equal guinea-pig units, the adonis extract, for instance, acts an capacitance vessels about twice as much as scilla, oleander and convallaria extracts. Cymarin, too, has a stronger effect an veins than would be expected from its cardiotoxic effect. The action an arteries and veins are based an different mechanism. Evidently the first one is mediated by x-adrenergic receptors, as it can be suppressed by phentolamine, while the latter is due to a non adrenergic attack at the smooth muscle cells of vein walls.
Keyword(s): Capacitance vessels