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 choline- acetyltransferase activities on autopsy samples of coronary vessels with the aim of inves- tigating age-related changes. Methods: Samples of human coronary vessels were harvested and exposed to the enzy- matic staining for acetylcholinesterase, immunohistochemical staining for cholineacetyl- transferase and quantitative analysis of images. Morphometric values were subjected to statistical analysis of data. Results: Our results demonstrated that both acetylcholinesterase and cholineacetyl- transferase 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. Cor- onary arterioles of large caliber (diameter > 150 mm) were found to have many cholinergic nerve fibers. The quantitative analysis of images and the statistical analysis of the data dem- onstrated 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 coro- nary 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.