Figure 3. Cardiac ganglion innervation patterns of ACP and ACV neurons.

a, Strategy for labeling ACP or ACV cardiac terminals by delivering AAV-DIO-eYFP encoding Cre-dependent eYFP reporter (green) to left (L) or right (R) Amb in Calb1^cre (ACP driver) or Ghsr^cre (ACV driver) mice. b, Immunostaining of ACP terminals (labeled with eYFP in Calb1^cre mouse) in inferior pulmonary veins GP (dotted outline). Bar, 20 μm. Inset: close-up of boxed region showing two cardiac ganglion neurons (dashed outlines), one (tACP, target of ACP) with eYFP-positive ACP input that was also Calbindin+ (ACP marker) and vesicular acetylcholine transporter (VAChT)+. An adjacent cardiac ganglion neuron ((tACV), putative target of ACV) received eYFP-, Calbindin-, VAChT+ pre-ganglionic input (red puncta), indicating it was not innervated by an ACP, but likely by an ACV neuron. Bar, 10 μm. c, Schematic of typical ACP and ACV innervation pattern of individual cardiac ganglion neurons (grey circles) within a GP. ACP fibers (dark blue) provide all cholinergic input for tACP neurons. ACV fibers (light blue) provide all innervation for tACV neurons, which are intermingled with tACP neurons. d, Immunostaining of ACV terminals (labeled as above with eYFP in a Ghsr^cre mouse) in two cardiac ganglion neurons (dashed outlines), one (tACV) with eYFP+, Calbindin-, VAChT+ ACV input. An adjacent cardiac ganglion neuron, (tACP), received eYFP-, Calbindin+, VAChT+ input, so was not innervated by an ACV but likely by an ACP neuron. Bar, 10 μm.