Fig. 7.

Effects of changing Saz-A preincubation concentration on LSP and HSP ACh-induced responses. X. laevis oocytes injected with unmodified LSP (A) and HSP (B) mRNA were first exposed to a maximally effective ACh control challenge, followed by pretreatment with Saz-A (5 minutes, concentrations indicated in legends). Concentration-response data were then collected using a series of acute ACh challenges (1 second, concentrations specified on the x axis; log M scale, see Materials and Methods for details). All concentration-response data were normalized to the initial control stimulation, in each oocyte (mean ± S.E.M., n = 3). For LSP α4β2-nAChR, Saz-A preincubation reduced (1 nM) and then abolished (> 3.16 nM) HS-phase responses. ACh EC₅₀ values and magnitudes of LS-phase responses were unaffected by increasing Saz-A preincubation concentrations (3.16–31.6 nM; pharmacological parameters reported in the text). For HSP α4β2-nAChRs, ACh responses were reduced by 1 nM Saz-A preincubation but, in contrast to LSP responses, no function remained after 31.6 nM Saz-A preincubation.