[Metoclopramide antagonizes dopamine-induced inhibition of lower esophageal sphincter pressure in the awake beagle].

Different contradictory results, even in the same species of the DOP-effect on LESP have been reported. The aim of the present studies was to evaluate the effect of DOP on LES in purebread male beagles and whether in could be antagonised by the DOP-antagonist MCP. The LESP in beagles is sensitive to dopamine (DOP) and its "antagonist", metoclopramide (MCP). MCP raised the inhibited LESP after DOP-infusion in vivo, while it failed to change DOP-induced relaxation of opossum LES in vitro [1]. Data obtained after monotherapie with MCP did not exceed LESP-response to MCP after DOP-pretreatment. DOP applied as background counter-inhibition could be used to correct interdigestive phasic changements of LESP in order to reach a stable starting-point to investigate the action of LESP-stimulating compounds pharmacomanometrically. Due to DOP reflux-facilitating side effect via its decrease of LESP, large doses of DOP, as used in the intensiv care unit, should be administered together with sphincter-strengthening agents or antacid compounds.