Effect of dopamine on prostaglandin E2 content in gastric mucosa.

The effects of dopamine (DA) on the prostaglandin (PG) E2 content of rat gastric mucosa was investigated. There was a 17.5% increase in gastric mucosal blood flow (BF) after administration of DA (5 micrograms/kg/min iv). After pretreatment with fusaric acid (FA), an antagonist of dopamine beta hydroxylase, DA increased BF by 27.8%. The PGE2 content in DA and DA + FA groups increased at rates of 45.8% and 42.4%, respectively. The PGE2 content in gastric mucosa after incubation following Basso's method, increased in the DA, DA + FA and noradrenaline (NA) groups to 3.32 +/- 0.40 micrograms/g, 3.30 +/- 0.39 micrograms/g and 3.37 +/- 0.42 micrograms/g respectively. It is concluded that there are no differences in PGE2 content among the DA, DA + FA and NA groups. The mechanism by which PGE2 content increases after administration of DA is the direct action of DA and/or increasing BF. It is suspected that DA directly affects PGE2 synthesis, however the possibility that DA is metabolized to NA, which secondarily results in increased PGE2 synthesis, cannot be excluded.