AIM:To investigate omeprazole-induced transepithelial gastric leak and its effects on the permeability of the peptides bradykinin and oxytocin.METHODS:Rat gastric corpus tissue was isolated and mounted in an Ussing chamber apparatus to evaluate the permeability of 3H-bradykinin,3H-oxytocin,and 14CEDTA in the presence or absence of omeprazole.Thinlayer chromatography was performed to identify any metabolic breakdown products of the peptides resulting from permeation through the gastric tissue,and thereby calculate the true flux of the peptide.RESULTS:The flux rate ofintact 3H-bradykinin increased substantially after omeprazole addition (109.5%) compared to the DMSO vehicle control (14%).No corresponding change in flux ofintact 3H-oxytocin was observed under the same conditions (11.9% and 6.4% in the DMSO-and omeprazole-treated conditions,respectively).After exposure to omeprazole,the flux rate of 14C-EDTA also increased dramatically (122.3%) compared to the DMSO condition (36.3%).CONCLUSION:The omeprazole-induced gastric leak allows for transmucosal permeability to charged molecules as well as non-electrolytes.This induced leak will allow certain peptides to permeate. AIM: To investigate omeprazole-induced transepithelial gastric leak and its effects on the permeability of the peptides bradykinin and oxytocin. METHODS: Rat gastric corpus tissue was isolated and mounted in an Ussing chamber apparatus to evaluate the permeability of 3H-bradykinin, 3H-oxytocin , and 14 CEDTA in the presence or absence of omeprazole.Thinlayer chromatography was performed to identify any metabolic breakdown products of the peptides resulting from permeation through the gastric tissue, and thereby calculate the true flux of the peptide .RESULTS: The flux rate of intact 3H- No corresponding change in flux of intact 3H-oxytocin was observed under the same conditions (11.9% and 6.4% in the DMSO-and omeprazole-treated conditions, respectively). After flux to omeprazole, the flux rate of 14C-EDTA also increased dramatically (122.3%) compared to the DMSO condition (36.3%). CONCLU SION: The omeprazole-induced gastric leak allows for transmucosal permeability to charged molecules as well as non-electrolytes.This induced leak will allow certain peptides to permeate.