Fig. 4.

Saz-A pretreatment effects on HSP versus LSP α4β2-nAChR function. X. laevis oocytes injected with mRNA encoding either wild-type HSP α4β2-nAChR or wild-type LSP α4β2-nAChR were tested for the effects of Saz-A (5-minute) pretreatment on subsequent, acute, agonist stimulation. Initial control stimulation was performed for 1 second, using a maximally effective concentration of ACh (30 µM for HSP, 1 mM for LSP). Oocytes were then exposed to Saz-A (3.16 nM) for 5 minutes, and the ACh challenge was repeated (1-second stimulation, coapplied with 3.16 nM Saz-A); typical traces are shown. Saz-A pretreatment greatly reduced HSP responses (peak response diminished to 17.6 ± 2.1%; mean ± S.E.M., n = 4). In contrast, Saz-A pretreatment diminished LSP peak responses to 33.3 ± 3.0% (mean ± S.E.M., n = 4). The difference in response to Saz-A pretreatment between HSP and LSP was significant (unpaired two-tailed t test, t = 4.21 with 6 degrees of freedom; P < 0.01).