Mean concentration-response curves for nicotine in longitudinal ileum preparation obtained from WT or β-arrestin2 KO mice.

<p>A slight but insignificant change to the sensitivity to nicotine was observed in the β-arrestin2 knockout mice (A). B) representative isometric tension recording tracing of the longitudinal ileum preparation from C57BL/6 WT mice showing the non-cumulative dose response effect of repeated exposure with nicotine. Statistically significant differences (p≤0.05) are identified by *.