Fig. 5.

Influence of α7 nAChR mutations on the allosteric modulatory effect of furosemide. The docked position of furosemide is shown in the closed (A) and open (B) structural model of the α7 nAChR transmembrane region. The TM1-3 helices of the principal subunit (khaki) and TM2 and TM3 helices of the complimentary subunit (green) are shown. Amino acids examined by site-directed mutagenesis are indicated. C) ACh dose-response curves determined with wild-type α7 nAChR (dashed line) and with α7 nAChRs containing single point mutations S222M, L247A, S248A, M260L and T288A. Data are means of at least three independent experiments. D) Bar chart illustrating the influence of furosemide (1 mM) on responses to an EC₅₀ concentration of ACh (10 μM for L247A and 100 μM for wild-type and all other mutated receptors). Data are normalised to the response observed in the same oocyte in the absence of furosemide. Data are means ± SEM of at least three independent experiments. Significant differences from wild-type are indicated (*P < 0.05, **P < 0.01). In addition, significant differences from agonist responses in the absence of furosemide are indicated (#P < 0.05, ##P < 0.01). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)