5-HT2A receptor is the predominant receptor mediating contraction of the isolated porcine distal ureter to 5-HT in young and old animals.

Isolated ureteral strips develop spontaneous phasic contractile activity which is enhanced by 5-hydroytryptamine (5-HT). The aim of this study was to identify the receptor subtype mediating these responses and to determine whether responses to 5-HT change with age. The frequency of contractions and the overall contractile activity (measured as the area under the curve, AUC) were recorded in strips of porcine distal ureter isolated from young (3 months) and old (2 years) pigs. Responses to 5-HT were examined in the absence and presence of selective 5-HT receptor subtype antagonists. Tissues from the younger animals elicited larger contractile responses to 5-HT (5885 ± 335g