Fig. 8. Identification of antagonists of 5-HT_2β and 5-HT₁. (A) Putative antagonists have no effect on the parental HEK cell line (left). Several of the antagonists (10^–5 mol l^–1) block 5-HT (1 mmol l^–1)-stimulated increases in IP levels in cells expressing 5-HT_2βPro (right). Values are means ± s.e.m., N=3, ^*P<0.05 vs 5-HT only. (B) Antagonist drugs have no significant effect on non-induced 5-HT_1Pro cells (left). None of these drugs (10 mmol l^–1) blocks inhibition of adenylyl cyclase by 10^–5 mol l^–1 5-HT in cells induced to express 5-HT_1Pro (right). Some putative antagonists actually increase the efficacy of the 5-HT effect. Values are means ± s.e.m., N=3, ^*P<0.05 vs 5-HT only.