Bravo capsule system optimizes intragastric pH monitoring over prolonged time: effects of ghrelin on gastric acid and hormone secretion in the rat.
OBJECTIVE
To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time.


METHODS
A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutive days. For comparison, a gastric fistula model was used. Effects of ghrelin and esomeprazole, with or without pentagastrin, on gastric pH were studied. In addition, effects of esomeprazole on plasma ghrelin, gastrin and somatostatin were analyzed.


RESULTS
All rats recovered after surgery. The average 24-h pH during free feeding was 2.3 +/- 0.1 (n = 20) with a variation of 18% +/- 6% over 5 d. Ghrelin, 2400 pmol/kg, t.i.d. increased pH from 1.7 +/- 0.1 to 3.1 +/- 0.3 (P < 0.01) as recorded with the Bravo system. After esomeprazole (1 mg/kg, 3 mg/kg and 5 mg/kg) there was a dose-dependent pH increase of maximally 3.4 +/- 0.1, with day-to-day variation over the entire period of 8% +/- 3%. The fistula and pH studies generated similar results. Acid inhibition with esomeprazole increased plasma ghrelin from 10 +/- 2 pmol/L to 65 +/- 26 pmol/L (P < 0.001), and somatostatin from 10 +/- 2 pmol/L to 67 +/- 18 pmol/L (P < 0.001).


CONCLUSIONS
pH measurements with the Bravo capsule are reliable, and comparable to those of the gastric fistula model. The Bravo system optimizes accurate intragastric pH monitoring over prolonged periods and allows both short- and long-term evaluation of effects of drugs and hormones.
Rudholm
Tobias
T
Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden. tobias.rudholm@ki.se
Hellstrom
Per-Mikael
PM
Theodorsson
Elvar
E
Campbell
Colin-Allan
CA
McLean
Peter-Geoffrey
PG
Naslund
Erik
E
D000818:Animals; D053705:Capsule Endoscopes; D053704:Capsule Endoscopy; D004195:Disease Models, Animal; D064098:Esomeprazole / Q000494:pharmacology; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination / Q000295:instrumentation*; D005747:Gastric Fistula / Q000378:metabolism / Q000503:physiopathology*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D005755:Gastrins / Q000378:metabolism; D005765:Gastrointestinal Agents / Q000494:pharmacology; D005768:Gastrointestinal Hormones / Q000378:metabolism*; D054439:Ghrelin / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation; D010418:Pentagastrin / Q000494:pharmacology; D054328:Proton Pump Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013004:Somatostatin / Q000378:metabolism; D013686:Telemetry / Q000295:instrumentation; D013997:Time Factors
D005755:Gastrins; D005765:Gastrointestinal Agents; D005768:Gastrointestinal Hormones; D054439:Ghrelin; D054328:Proton Pump Inhibitors; D013004:Somatostatin; D010418:Pentagastrin; D064098:Esomeprazole