[The effects of H. pylori and its crude extracted proteins on isolated rabbit parietal cells acid secretion].
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 (100 microLg/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 alpha 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 alpha 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 x 10(-4) 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 alpha subunit mRNA expression was up-regulated in the 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 alpha 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.
Guo
Tao
T
Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
Zhao
Yu-Qing
YQ
Qian
Jia-Ming
JM
Li
Xiao-Bo
XB
Zhang
Jian-Zhong
JZ
D000818:Animals; D001426:Bacterial Proteins / Q000302:isolation & purification; D005744:Gastric Acid / Q000378:metabolism*; D017506:H(+)-K(+)-Exchanging ATPase / Q000096:biosynthesis; D016480:Helicobacter pylori; D008297:Male; D010295:Parietal Cells, Gastric / Q000378:metabolism*; D011817:Rabbits
D001426:Bacterial Proteins; D017506:H(+)-K(+)-Exchanging ATPase