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Arachidonic acid- and acetylcholine-induced relaxations of rabbit aorta. Hypertension 1992 Nov;20(5):682-9 PMID: 1330923

Pubmed ID

1330923

Abstract

The present study investigated the role of arachidonic acid and acetylcholine in mediating endothelium-dependent relaxations of rabbit aorta. Isolated thoracic aortic rings were precontracted with a submaximal concentration of norepinephrine, and the effect of various agents on arachidonic acid- and acetylcholine-induced relaxations was examined. Arachidonic acid elicited a concentration-related relaxation that was potentiated by the cyclooxygenase inhibitor indomethacin. Treatment with the lipoxygenase inhibitor nordihydroguaiaretic acid completely blocked but the cytochrome P450 inhibitor metyrapone had no effect on arachidonic acid-induced relaxation. NG-Monomethyl-L-arginine and nitro-L-arginine, compounds that inhibit the nitric oxide-like endothelium-derived relaxing factor, had little or no effect on arachidonic acid-induced relaxations. In contrast, nordihydroguaiaretic acid, metyrapone, NG-monomethyl-L-arginine, and nitro-L-arginine all attenuated the relaxation to acetylcholine; however, indomethacin had no effect on acetylcholine-induced relaxations. Arachidonic acid and acetylcholine had no effect on denuded rabbit aorta. Incubation of rabbit aorta with [14C]arachidonic acid resulted in the synthesis of major radioactive metabolites that comigrated with the prostaglandins and hydroxyeicosatetraenoic acids. Indomethacin selectively inhibited prostaglandin formation, nordihydroguaiaretic acid attenuated both prostaglandins and hydroxyeicosatetraenoic acids, and metyrapone blocked the epoxyeicosatrienoic acids. Additionally, acetylcholine elicited a twofold increase in tissue cyclic guanosine monophosphate content in contrast to a 59% reduction in cyclic guanosine monophosphate content observed with arachidonic acid. Therefore, these data suggest that in rabbit aorta, arachidonic acid-induced relaxations are mediated by an endothelium-dependent factor (or factors) that differs from the factor (or factors) released by acetylcholine. These results support the existence of multiple endothelium-derived relaxing factors.

Author List

Pfister SL, Campbell WB

Authors

William B. Campbell PhD Chair, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin
Sandra L. Pfister PhD Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin




Scopus

2-s2.0-0026781965   34 Citations

MESH terms used to index this publication - Major topics in bold

Acetylcholine
Animals
Aorta
Arachidonic Acid
Arginine
Bridged Bicyclo Compounds, Heterocyclic
Cyclic GMP
Fatty Acids, Unsaturated
Hydrazines
Indomethacin
Male
Masoprocol
Metyrapone
Nitroarginine
Rabbits
Receptors, Thromboxane
Vasodilation
jenkins-FCD Prod-353 9ccd8489072cb19f5b9f808bb23ed672c582f41e