[Effect of kynurenines on the actions of acetylcholine, oxotremorine, and nicotine].

Kynurenine, 3-hydroxyanthranilic, anthranilic and nicotinic acids at concentrations 10(-4) and 10(-5) M potentiated contractions of the isolated rat rectum produced by acetylcholine. Contractile response of the phrenico-diaphragmatic preparation of young rats to acetylcholine was diminished by kynurenine, 3-hydroxykynurenine and by quinolinic acid. In rats of both sexes, 3-hydroxyanthranilic, anthranilic, picolinic and nicotinic acids in doses of 10 and 20 mg/kg shortened the latency of oxotremorine tremor.

[Effect of kynurenine and its metabolites on the vascular effects of serotonin, noradrenaline, and acetylcholine].

In female albino rats anesthetized with urethane, the depressor effect of serotonin was basically diminished by kynurenine, 3-hydroxyanthranilic acid (3-HAA), and anthranilic acid and was potentiated by quinolinic and picolinic acids (PA). All kynurenines were injected in a dose of 200 micrograms. 3-Hydroxykynurenine and nicotinic acid (NA) had a dual action.