Figure 4.
Deletion of ChAT in adult sympathetic neurons prevents the increase in left ventricle ACh after MI. A, Expression of cholinergic genes. ChAT, CHT, and VAChT mRNA were quantified 14 d after MI in ChATDBHCreERT2/lox mice that had been treated with tamoxifen for 7 d (iChAT KO) and normalized to GAPDH mRNA in the same samples. Data are graphed as a percentage of control using the levels of each gene previously observed in WT mice 14 d post-MI as the control values (dotted black line). ChAT mRNA was present at levels similar to sham controls and was significantly lower than WT post-MI mice, whereas CHT and VAChT mRNA levels were not significantly different from WT mice after MI. B, Ventricular ACh and NE. The loss of the ChAT gene in sympathetic neurons resulted in ACh levels 14 d after MI that were similar to sham hearts and significantly lower than the post-MI levels previously identified in WT mice (dotted black line). NE levels were unchanged compared with WT mice. Data are shown as means ± SEM; n = 4; ****p < 0.0001 compared with WT 14 d post-MI. C, Parasympathetic control of heart rate. Heart rate was quantified in unoperated WT and iChAT KO mice before and after atropine injection (mean ± SEM, n = 3).