Serotonin type 3 receptor subunit gene polymorphisms associated with psychosomatic symptoms in irritable bowel syndrome: A multicenter retrospective study

Figure 2 Comparative analysis of 5-HT₃AC 163N (major allele homozygous), 5-HT₃AC 163K (minor allele homozygous), and 5-HT₃AC 163K/163N (heterozygous) receptors. A: Radioligand-binding studies Saturation experiments were performed in membranes of HEK293 cells transiently expressing different 5-HT₃ subunit combinations in triplicate with six increasing concentrations of [3H]GR65630 (0.02-1.5 nmol/L); Kd values were 0.07 ± 0.01 for 5-HT₃AC 163N; 0.08 ± 0.01 for 5-HT₃AC 163K, and 0.07 ± 0.01 for 5-HT₃AC 163K/163N. n = 6 experiments; B: Concentration response curves were assessed in a calcium influx assay (aequorin assay) in HEK293 cells transiently transfected with different 5-HT₃ subunit combinations in quadruplicate with seven increasing concentrations of 5-HT. pEC50 values were as follows: 68 ± 0.03 for 5-HT₃AC 163N 5 and 5.66 ± 0.02 for 5-HT₃AC 163K; C: Respective maximal calcium influx values (E_max) evoked by 5-HT (10 μmol/L). Data are expressed as percentages of the E_max of the heteromeric 5-HT₃AC 163N receptor (% of control), n = 8 experiments. Bars represent mean ± SE. ^bP < 0.01 from ANOVA followed by Dunnett’s post-test or unpaired Student’s test for comparison of only two groups.