Patch Clamp Study of Serotonin-Gated Currents via 5-HT Type 3 Receptors by Using a Novel Approach SHAM forReceptor Channel Scanning

[摘要] We studied 5-hydroxy tryptamine type 3 (5-HT3) receptorstransfected in tsA-201 cell line to examine serotonin-inducedwhole cell currents. Using the site-directed mutagenesistechnique, we individually mutated each residue in themembrane-spanning M2 segment to histidine. A high proportion oftsA-201 cells cotransfected with the cDNAs of 5-HT3R and CD8produced large amplitude responses (0.5–7.0 nA) toserotonin. The dose-response curve of wild-type (WT) receptorranging from 0.5 to 500μmole increases its Kdvalues, andImaxof 5-HT3R falls at low external pH as ifprotonation of an acid group is enough to block the channel.Lysine at position 281, a basic residue, is more susceptible toacidification-induced blockade of the 5-HT3R channel.Dose-response curves of K281S (replacing lysine at the 281position with serine) at different pH are not significantlymodulated, and histidine substitutions at the three consecutivepositions 293, 294, and 296 eliminate the pH block of the channel.

[学科分类] 基础医学