Histamine uptake and its methylation by isolated oxyntic cells

The role of the oxyntic cells in the inactivation and elimination of histamine was studied in dispersed and isolated mucosal cells. Gastric mucosal cells from rabbits were incubated with 14C-labelled histamine (1 and 3.2 X 10(-6) M) at 37 degrees C. Histamine and the histamine metabolites were extracted, separated on thin layer chromatography, and quantitated. Both the intracellular and extracellular compartments were examined. Gastric mucosal cells were found to internalize histamine and methylate it to Nt-methylhistamine, a biologically inactive metabolite. This process was Na+-dependent and occurred primarily in the oxyntic cells. Ethanol in concentrations between 1 to 4% decreased histamine methylation. The histamine content associated with the intracellular compartment was unaffected by ethanol. Pentagastrin (10(-10) to 10(-6) M) had no significant effect on histamine methylation. The results substantiate that oxyntic cells take up and inactivate histamine, and thus are capable of modifying extracellular histamine concentration. Ethanol inhibits histamine methylation, potentially maintaining or increasing extracellular histamine, while pentagastrin appears to have no significant effect.