Distribution of acetylcholinesterase and cholineacetyl-transferase activities in coronary vessels of younger and older adults

Background:   The cholinergic nerve fibers of coronary arteries, capillaries and veins were studied in younger and older humans by staining of acetylcholinesterase and cholineacetyltransferase activities on autopsy samples of coronary vessels with the aim of investigating age-related changes.
Methods:   Samples of human coronary vessels were harvested and exposed to the enzymatic staining for acetylcholinesterase, immunohistochemical staining for cholineacetyltransferase and quantitative analysis of images. Morphometric values were subjected to statistical analysis of data.
Results:   Our results demonstrated that both acetylcholinesterase and cholineacetyltransferase are localized in the coronary vessels of younger and older humans. Staining of these two enzymes showed specific age-related changes. Structures resembling cholinergic nerve fibers were located in coronary vessels, in the extra-parenchymal (large caliber) and intraparenchymal (small caliber) branches (arteries and veins), organized in a plexus. Coronary arterioles of large caliber (diameter > 150 µm) were found to have many cholinergic nerve fibers. The quantitative analysis of images and the statistical analysis of the data demonstrated that the cholinergic neurotransmitters of coronary vessels (especially the extra-parenchymal branches of coronary arteries) strongly decrease with age.
Conclusions:   The age-related changes of cholinergic nerve supply of the human coronary vessels may play a role in the control of coronary circulation. Further studies are needed in order to draw definite conclusions concerning the nervous control of coronary circulation under normal and/or pathological conditions.