Docosahexaenoic acid inhibits U46619- and prostaglandin F 2α -induced pig coronary and basilar artery contractions by inhibiting prostanoid TP receptors.

Docosahexaenoic acid (DHA, an n-3 polyunsaturated fatty acid) inhibits U46619 (a TP receptor agonist)- and prostaglandin F _2α -induced contractions in rat aorta and mesenteric arteries. However, whether these effects could be replicated in vasospasm-prone vessels, such as coronary and cerebral arteries, remains unknown. Here, we evaluated the changes in pig coronary and basilar artery tensions and intracellular Ca ²⁺ concentrations in human prostanoid TP or FP receptor-expressing cells. We aimed to clarify whether DHA inhibits U46619- and prostaglandin F _2α -induced contractions in spasm-prone blood vessels and determine if the TP receptor is the primary target for DHA. In both pig coronary and basilar arteries, DHA suppressed U46619- and prostaglandin F _2α -induced sustained contractions in a concentration-dependent manner, but did not affect contractions induced by 80 mM KCl. SQ 29,548 (a TP receptor antagonist) suppressed U46619- and prostaglandin F _2α -induced contractions by approximately 100% and 60%, respectively. DHA suppressed both U46619- and prostaglandin F _2α- induced increases in intracellular Ca ²⁺ concentrations in human TP receptor-expressing cells. However, DHA did not affect prostaglandin F _2α- induced increases in intracellular Ca ²⁺ concentrations in human FP receptor-expressing cells. These findings suggest that DHA potently inhibits TP receptor-mediated contractions in pig coronary and basilar arteries, and the primary mechanism underlying its inhibitory effects on arterial contractions involves inhibiting TP receptors.
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