A, B, Stellate ganglion sections 14 d after sham (A) or MI (B) stained for TH (red) to identify noradrenergic neurons and ChAT (green) to identify cholinergic neurons. Scale bar, 50 μm. In sham ganglia, only preganglionic fibers are positive for ChAT, whereas sympathetic cell bodies are TH+. After MI, however, TH+ sympathetic neurons also express ChAT. C, D, Heart sections after sham (C) or MI (D) stained for TH (red) and VAChT (green). Scale bar, 100 μm. Yellow arrowheads identify TH+/VAChT− sympathetic fibers; white arrowheads identify TH−/VAChT+ parasympathetic fibers; blue arrows identify fibers positive for both noradrenergic and cholinergic markers, which were observed only after MI. Note that parasympathetic fibers are sparse in the left ventricle whereas sympathetic fibers are abundant.