Endothelium-induced relaxation by acetylcholine associated with larger rises in cyclic GMP in coronary arterial strips.

It was previously shown that the contractile response to acetylcholine (ACh) in bovine coronary arterial strips could be separated from the accompanying rises in cGMP in an opposite manner which suggested that this nucleotide may function as a relaxation- rather than a contraction promoting agent. It was also found recently by others that rings or strips of rabbit aorta and other arteries of various species relax in response to ACh if endothelial cells are still present. The influence of endothelium on the mechanical effects as well as on rises in cGMP levels produced by ACh was therefore studied in circular strips of bovine coronary arteries with and without endothelium.