A histamine H4 receptor agonist (Kis 5.01 and 14.13 for the human and rat receptors respectively) selective for the rat histamine H4 receptor over the rat histamine H3 receptor (Kis 34.67 and 1778.28 nM respectively) potentiates the formation of HCl-induced ulcers in the rat gastric mucosa at 10 mg/kg an effect that is not blocked by the histamine H4 receptor antagonist JNJ-7777120