Heterogeneity of 5‐hydroxytryptamine receptors in the rat uterus and stomach strip

Abstract

Experiments were performed using the rat isolated uterus and the rat stomach strip to investigate the effects of 5-hydroxytryptamine (5-HT) on 5-HT receptors in the presence of different antagonists. Amitriptyline, methysergide and trazodone were used to antagonize the response to 5-HT in these tissues. The pA2 [competitive antagonistic activity] value for amitriptyline with 5-HT as the agonist was estimated from the Schild plot analysis and differed significantly (P < 0.05) in the stomach strip (6.36) from that in the isolated uterus (9.06). A similar difference was found using trazodone; the pA2 value was 6.74 in the stomach strip and 8.49 in the isolated uterus. A difference between the 2 tissues is indicated. This difference is discussed in terms of heterogeneity of 5-HT receptors.