Fig. 4.

Confocal images of the immunofluorescence surface detection of the α4 subunit after chronic nicotine exposure. (a) Fluorescence intensity of oocytes injected with wild-type α4β2. The initial response at 300 µM ACh for the incubated oocyte was 3,333 and 2,834 nA for the control oocyte. (b) Fluorescence intensity of oocytes injected with α4S336A mutant. The initial responses at 300 µM ACh for the incubated and control ocytes were 1,968 and 1,704 nA, respectively. (c) Fluorescence intensity of oocytes injected with α4S336D mutant. The initial response at 300 µM ACh for the incubated oocyte was 1,830 and 1,876 nA for the control oocyte. (d) Fluorescence intensity of oocyte not injected but treated with primary and secondary antibodies (left). Oocyte injected with wild-type α4β2 (335 nA) but treated with primary antibody (right). (e) The average n-fold values are presented as bar graphs for wild-type (black), α4S336A (red), and α4S336D (blue)