Histochemical localization of acetylcholinesterase in the wall of cardiac blood vessels in the baboon, dog and vervet monkey.

Histochemical methods were used to demonstrate acetylcholinesterase in the wall of cardiac blood vessels in the baboon, dog and vervet monkey. To remove cholinesterase-containing sympathetic nerves, some of the animals were treated with guanethidine for four weeks prior to being sacrificed. In cardiac muscle from the dog and the vervet monkey, cholinergic nerves were histochemically visualized in both small and large vessels. On the other hand, in cardiac muscle from baboons, cholinergic nerves were not seen in branches of the coronary artery with diameters between 0.6 mm to 1 mm and very few fibres were seen around smaller vessels of diameter less than 0.3 mm. The few fibres seen did not appear to penetrate the media of the vessels. These results support physiological findings that the baboon coronary vasculature is not innervated by parasympathetic cholinergic nerves.