抄録
The contractile effects of serotonin and 5-hydroxykynurenamine (5-HK) on isolated guinea-pig trachea were investigated.
Male Hartley strain guinea-pigs, weighing 250-300g, were killed. Guinea-pig tracheal strips were removed, spirally cut and suspended in a bioassay glass chamber and superfused with Krebs-Hensleit solution at 37°C saturated with oxygen and carbon dioxide (95:5, v/v). Contractile response of guinea-pig tracheal strips was detected by an isotonic transducer and recorded on a polyrecorder.
1) Serotonin and 5-HK caused dose-releated contractions in the guinea-pig tracheal strips. However the effect of 5-HK was approximately 1% that of serotonin.
2) The contractile response to serotonin was attenuated by continuous infusion of 5-HK (5×10-8M).
3) The contractile response to acetylcholine was not reduced by continuous infusion of 5-HK.
4) The contractile response to 5-HK was attenuated by methysergide.
5) Treatment with 5-HK caused a dose-related inhibition in the contractile response to serotonin (5×10-4M).
6) The above findings may suggest that 5-HK, a new serotonin metabolite, and serotonin share receptors in the guinea-pig trachea and that the effect of serotonin is specifically antagonized by 5-HK.
