Prostaglandins, antipyretic analgesics and adrenergic stimuli on the isolated artery

In untreated, and cocaine- and DOCA-treated rabbit ear arteries, PGE 2 and arachidonic acid depressed the responses to intramural sympathetic nerve stimulation. Constrictor responses to extraluminal NA in the treated arteries were also depressed. A comparison of its inhibitory potency on the two types of responses suggest that the effects of PGE 2 on responses to adrenergic nerve stimuli are due, in part, to depression of sensitivity to NA. The effects of arachidonic acid, but not PGE 2 on adrenergic nerve stimuli, were selectively blocked by aspirin 200 μg/ml and by indomethacin 3 μg/ml. In these concentrations, aspirin, but not indomethacin, enhanced the magnitude of the responses to the stimuli. Aspirin also selectively reduced the inhibition by arachidonic acid of the response to extraluminal NA (tested in cocaine- and DOCA-treated arteries).