The effects of indomethacin and eicosa-5,8,11,14-tetraynoic acid on the response of the rabbit portal vein to electrical stimulation.

1 The effects of indomethacin and eicosa-5,8,11,14-tetraynoic acid (ETYA) on the contractile response of the transmurally stimulated rabbit portal vein were studied in vitro.2 When the veins were stimulated for 240 pulses at 1 and 2 Hz, the responses were potentiated by indomethacin and ETYA. However, responses to 4 and 8 Hz were not potentiated. The responses to continuous electrical stimulation at 2 Hz were also potentiated by indomethacin and ETYA. This potentiating effect was attenuated when the veins were pretreated with alpha-methyl-p-tyrosine. The responses of the veins to noradrenaline were not altered by either indomethacin or ETYA.3 Prostaglandin E(2) inhibited the responses of the portal vein to electrical stimulation. The magnitude of this inhibition was inversely related to the frequency of stimulation. The responses of the vein to noradrenaline were not altered by prostaglandin E(2).4 It is concluded that potentiation by indomethacin and ETYA of the response of the isolated portal vein is due to an increased release of newly synthesized noradrenaline as a result of inhibition of prostaglandin synthesis.