Die wirkung der β-adrenergischen substanz isoprenalin auf die ausfluß-fazilität des kaninchenauges

Zusammenfassung

Dasdl-Isoprenalinsulfat bewirkt in Dosen von 5 µg subconjunctival innerhalb 30 min und in Konzentrationen von 10 bzw. 100 µg intravitreal innerhalb 70 min eine Fazilitätsverbesserung von 0,11–0,17 µll min⁻¹ mm Hg⁻¹ beim Albino-Kaninchen. Der Anteil der Pseudofazilität an der gesamten Fazilitätsverbesserung ist gering. Die Fazilitätssteigerung ist als echterβ-Effekt aufzufassen, da im sympathisch chronisch-denervierten Auge keine Sensibilisierung, aber auch keine Unterempfindlichkeit gegenüber Isoprenalin zu beobachten ist. Versuche, die Isoprenalin-Wirkung durch denβ-Blocker Nethalid zu antagonisieren mißBlangen, wahrscheinlich deshalb, veil nicht genügend hohe Konzentrationen von Nethalid erreicht werden konnten. Es scheint also der Kammerwinkel des Kaninchenauges zu denjenigen Systemen zu gehören, die auf α- undβ-adrenergische Stimuli gleichsinnig reagieren.

Summary

The eyes of albino rabbits were injected subconjunctivally or intravitreally withdl-isoprenaline-sulphate and outflow facility measured after cannulation of the anterior chamber by the two-level constant-pressure infusion method. Within 30 minutes after subconjunctival injection of 5 µg (of the salt) and around 70 minutes after the intravitreal injection of 10 µg or 100 µg, facility was increased by 0.11–0.17 µl min⁻¹ mm Hg⁻¹. The increase persisted for some time after the animal was killed and was not markedly different in eyes which had been sympathetically denervated by removal of the superior cervival ganglion on the same side 3 weeks before the experiment. Attempts to reverse the facility increase by 10 mg/kg intravenous nethalide, an antagonist of adrenergicβ-action were unsuccessful. Injection into the vitreous of a mixture of up to 250 µg nethalide and 10 µg isoprenaline sulphate caused a facility increase that did not differ significantly from that cause by isoprenaline alone.

Despite the inability of nethalide to block it — which may be a question of dosage — the facility effect of isoprenaline is considered to be aβ-adrenergic one, since it was not enhanced by denervation. The fact that it persisted in spite of denervation indicates that it was not due to release of α-adrenergic transmitter by the excess isoprenaline. It therefore seems that the outflow system of the rabbit eye reacts similarly to a-adrenergic andβ-adrenergic stimuli.