Effects of 5-Hydroxykynurenamine, a New Serotonin Metabolite, on Isolated Dog Basilar Arteries

  1. Noboru Toda*,
  2. Takashi Tokuyama†,
  3. Siro Senoh‡,
  4. Fusao Hirata§, and
  5. Osamu Hayaishi§
  1. *Department of Pharmacology, Kyoto University Faculty of Medicine, Kyoto
  2. §Department of Medical Chemistry, Kyoto University Faculty of Medicine, Kyoto
  3. †Department of Chemistry, Osaka City University Faculty of Science, Osaka
  4. ‡Central Research Institute, Suntory Ltd., Osaka, Japan

Abstract

Serotonin and 5-hydroxykynurenamine caused dose-related contractions in the spiral strips of dog basilar arteries. The potency of 5-hydroxykynurenamine was approximately 1/100 that of serotonin, the former frequently causing a transient relaxation preceding the contraction. The contractile responses to 5-hydroxykynurenamine and serotonin were attenuated by methysergide. Treatment with 5-hydroxykynurenamine inhibited the response to serotonin, and this inhibitory effect was not completely reversed by removal of 5-hydroxykynurenamine from the bathing medium. The contractile response to K+ was only slightly attenuated by high concentrations of 5-hydroxykynurenamine. It appears that 5-hydroxykynurenamine and serotonin share receptors in dog basilar arteries and that the effect of serotonin is specifically antagonized by 5-hydroxykynurenamine.

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  1. PNAS 1974-01 vol. 71 no. 1 122-124
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