Relationship between endogenous prostaglandin E and the vasoconstrictor response to noradrenaline in a perfused arterial segment.

The close interrelation between endogenous prostaglandin E (PGE) and the vasoconstrictor response to noradrenaline (NA) was evaluated using a perfused central arterial segment of a rabbit ear. The endogenous PGE level, measured radioimmunologically, was estimated from that in the perfusate. Pretreatment with arachidonic acid (AA) caused a decrease in the response to NA which was accompanied by a rise in the PGE level. The response to NA (% control) correlated significantly and negatively with the PGE level (ng/ml) in the perfusate. In addition, repetitively applied NA elicited gradual augmentation in the response to NA, which was accompanied by a reduction in the PGE level in the perfusate. These results seem to suggest that the endogenous PGE in the perfused central arterial segment of the rabbit ear is related to the inhibitory action on the response to NA.