Relaxant responses to CFP were expressed as a percentage of the
precontraction induced by methoxamine. The previously described
procedure was applied to intact and endothelium-denuded tissue.
It was also applied to another two groups of intact preparations;
one with the addition of NW-nitro-L-arginine methyl ester (LNAME)
(104 M), and the other one with the addition of indomethacin
(105 M). Both drugs were added to the organ bath 30 min before
methoxamine administration. The denuded endothelium
preparations were prepared by gently rubbing the tissue before it
was cut into rings. The efficacy of the procedure used to remove
the endothelial cells was judged by the loss of acetylcholine-induced
relaxation when the aorta preparations were precontracted
with methoxamine. According to the study published by Furchgott
in 1980 [7,8], the endothelial cells are necessary for this response.