The effects of H.pylori and its crude extracted proteins on isolated rabbit parietal cells acid secretion / 中华内科杂志

ABSTRACT

Objective To explore the effects of H.pylori and crude extracted proteins secreted by H.pylori(broth culture filtrate protein,BCF-P)on acid secretion from isolated rabbit parietal cells.Methods Parietal cells from rabbit gastric mucosa were isolated and enriched with digestion and elutriation.H.pylori(NCTC 11637,CagA+ VacA+)were grown in liquid broth culture and BCF-P was precipitated with ammonium sulfate.The vacuolation activity of BCF-P was evaluated with neutral red dye uptake test in HeLa cell.Isolated parietal cells were incubated with H.pylori(bacteria/cell=100∶1)for 2 h and 16 h,or BCF-P(100μg/ml)for 1 h and 12 h.Acid secretion from parietal cells was studied using 14C-aminopyrine(14C-AP)accumulation indirectly and H+-K+ ATPase α subunit mRNA expression was assessed using RT-PCR.Results (1)BCF-P containing vacuolating cytotoxin(VacA)with vacuolation activity on HeLa cells had positive result on neutral red uptake test.(2)The basal expression of H+-K+ ATPase α subunit mRNA could be detected in isolated parietal cells and 14C-AP accumulation was significantly increased in response to the stimulation of histamine with different concentrations for 30 min(P＜0.05).These results indicated that the isolated parietal cells retain relative intact acid secretion function.(3)The histamine(1.0×104 mol/L)stimulated acid secretion was inhibited sustainedly in response to H.pylori by 81% at 2 h and by 94% at 16 h(P＜0.05).However,H+-K+ ATPase α subunit mRNA expression was up-regulated in tlle acute period(2 h)and was down-regulated in the chronic period (16 h)by H.pylori(P＜0.05).(4)BCF-P significantly inhibited the histamine-stimulated acid secretion by 24% at 1 h and by 58% at 12 h(P＜0.05),and this inhibition was accompanied by the down-regulated expression of H+-K+ATPase α subunit mRNA.Conclusions Intact H.pylori and VacA secreted by H.pylori could directly inhibit histamine-stimulated acid secretion from parietal cells and this inhibition may be mediated by the down-regulated H+-K+ ATPase expression.