Ion permeation properties of a cloned human 5-HT3 receptor transiently expressed in HEK 293 cells.
Human 5-HT3 receptors expressed in HEK 293 cells were studied using patch-clamp techniques. The permeability ratios of cations to Na+ were Li+, 1.16; K+, 1.04; Rb+, 1.11; Cs+, 1.11; NMDG+, 0.04; Ca2+, 0.49, and Mg2+, 0.37. The permeability sequence of the alkali metal cations was Li+ > Rb+ = Cs+ > K+ > Na+. Increased external concentrations of Ca2+ or Mg2- decreased 5-HT-induced currents at all potentials tested in a voltage-independent manner. The single-channel conductance of human 5-HT3 receptors measured by fluctuation analysis of whole-cell currents was 790 +/- 100 fS. Differences in the basic properties of 5-HT3 receptors between species may explain interspecies differences in pharmacological properties.
Mochizuki
S
S
Molecular Medicine Laboratories, Yamanouchi Pharmaceutical Co., Ltd., Ibaraki, Japan. mochizuk@yamanouchi.co.jp
Miyake
A
A
Furuichi
K
K
D002412:Cations; D002460:Cell Line; D006801:Humans; D017136:Ion Transport; D018408:Patch-Clamp Techniques; D010539:Permeability; D011985:Receptors, Serotonin / Q000378:metabolism*; D044406:Receptors, Serotonin, 5-HT3; D011994:Recombinant Proteins / Q000378:metabolism
D002412:Cations; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D011994:Recombinant Proteins