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. 2003 Apr 28;100(10):6239–6244. doi: 10.1073/pnas.1037595100

Figure 1.

Figure 1

Receptor-mediated kinetics. This figure illustrates the basic characteristics of the receptor-mediated responses and a summary of the mean data obtained. (A) Representative current traces of cells from three different receptor + channel cell lines (D2S receptor, HKIR3.1/3.2/D2; α2A receptor, HKIR3.1/3.2/α2; GABA-B1b/2 receptor, HKIR3.1/3.2/GGB) voltage-clamped at −60 mV and exposed to agonist for 20 s (as indicated by the horizontal bar). We calculated a deactivation time constant (τ) as a measurement of channel-deactivation kinetics (as indicated) after the removal of agonist (see Materials and Methods). (B) Summary of deactivation data obtained from five cell lines expressing the Kir3.1 + 3.2A channel complex and the receptor indicated. Radioligand binding revealed similar levels of receptor expression in the HKIR3.1/3.2/A1, HKIR3.1/3.2/α2, and HKIR3.1/3.2/D2 cell lines (not shown); thus, we compared deactivation time constants in these three cell lines and found that deactivation was significantly faster in the HKIR3.1/3.2/A1 cell line than in the HKIR3.1/3.2/α2 and HKIR3.1/3.2/D2 cell lines (P < 0.01 and P < 0.05, respectively).