Dimaprit inhibition of zymosan-stimulated beta-glucuronidase release from human granulocytes

Abstract

Histamine inhibits the in vitro release of granulocytic lysosomal beta-glucuronidase when incubated with complement activated zymosan particles and this is an H2-receptor response. The highly specific histamine H2-receptor agonist, dimaprit, also inhibits this secretory enzyme release but is less potent (-log molar ED₅₀ 6.71 with histamine vs.-log ED₅₀ 5.97 with dimaprit,pK _B =2.9×10⁻⁸ M with histamine andK _B =3.6×10⁻⁸ M with dimaprit). Diphenhydramine did not change the granulocyte response to either histamine or dimaprit.