The effect of Helicobacter pylori on gastric acid secretion by isolated parietal cells from a guinea pig. Association with production of vacuolating toxin by H. pylori.
BACKGROUND
One of the features of Helicobacter pylori infection in the human stomach seems to be disordered gastric acid secretion. The effect of vacuolating toxin (VT) produced by H. pylori on gastric acid secretion was examined.


METHODS
VT(+)(toxigenic) and VT(-)(nontoxigenic) strains of H. pylori were cultured in brucella broth. The culture supernatant was added to isolated parietal cells, and acid secretion and intracellular adenosine 3'5'-cyclic phosphate (cAMP) and Ca2+ levels were measured with the 14C-aminopyrine (14C-AP) method, with 125I radioimmunoassay (RIA), and with the fura-2 fluorescence method, respectively.


RESULTS
In the VT(+) strain a considerable inhibitory effect on 14C-AP accumulation was observed. However, the VT(-) strain had no significant effect on intracellular c-AMP and Ca2+.


CONCLUSIONS
The VT(+) strain of H. pylori has an inhibitory effect on gastric acid secretion, whereas the VT(-) strain does not. This inhibitory effect was not associated with the response of second messengers. It is speculated that VT produced by H. pylori has a direct action on H(+)-K+ adenosine triphosphatase in parietal cells.
Kobayashi
H
H
Dept. of Internal Medicine 6, School of Medicine, Tokai University, Kanagawa, Japan.
Kamiya
S
S
Suzuki
T
T
Kohda
K
K
Muramatsu
S
S
Kurumada
T
T
Ohta
U
U
Miyazawa
M
M
Kimura
N
N
Mutoh
N
N
Shirai
T
T
Takagi
A
A
Harasawa
S
S
Tani
N
N
Miwa
T
T
D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000494:pharmacology; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D005744:Gastric Acid / Q000378:metabolism*; D006168:Guinea Pigs; D017506:H(+)-K(+)-Exchanging ATPase / Q000187:drug effects; D016480:Helicobacter pylori / Q000378:metabolism*; D008297:Male; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000378:metabolism*; D015290:Second Messenger Systems / Q000187:drug effects
D001426:Bacterial Proteins; D001427:Bacterial Toxins; C074689:VacA protein, Helicobacter pylori; D000242:Cyclic AMP; D017506:H(+)-K(+)-Exchanging ATPase; D002118:Calcium