Cloned human and murine serotonin(3A) receptors expressed in human embryonic kidney 293 cells display different single-channel kinetics.
In the present study, well-resolved single-channel events of cloned human and murine homomeric 5-hydroxytryptamine type 3 (h5-HT(3A) and m5-HT(3A)) receptors, expressed in human embryonic kidney 293 cells, are reported for the first time. 5-HT (1 microM) applied in Ca(2+)- and Mg(2+)-free external solution to excised outside-out membrane patches induced non-rectifying single-channel inward currents. These currents were not observed in untransfected cells or in the presence of the antagonist ondansetron (1 microM). The mean single-channel conductance of the h5-HT(3A) and m5-HT(3A) receptors was 48+/-8 pS and 46+/-7 pS, the mean reversal potential was 10.3+/-1.8 mV and 4.7+/-5.3 mV, respectively. The analysis of single-channel open-times revealed for both h5-HT(3A) and m5-HT(3A) receptors only one type of open state, but different mean open-times (7.1+/-2.9 ms vs. 4.1+/-0.8 ms) indicating species-dependent gating mechanisms of 5-HT(3) receptors.
Hapfelmeier
Gerhard
G
Department of Anaesthesiology, Technische Universität München, Munich, Germany. hapfelmeier@mpipsykl.mpg.de
Haseneder
Rainer
R
Lampadius
Katrin
K
Rammes
Gerhard
G
Rupprecht
Rainer
R
Zieglgänsberger
Walter
W
D000818:Animals; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D017294:Ondansetron / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011985:Receptors, Serotonin / Q000378:metabolism*; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists / Q000494:pharmacology; D013045:Species Specificity; D014162:Transfection
D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists; D017294:Ondansetron