Basic Research
Copyright ©2008 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Oct 28, 2008; 14(40): 6180-6187
Published online Oct 28, 2008. doi: 10.3748/wjg.14.6180
Bravo capsule system optimizes intragastric pH monitoring over prolonged time: Effects of ghrelin on gastric acid and hormone secretion in the rat
Tobias Rudholm, Per Mikael Hellström, Elvar Theodorsson, Colin Allan Campbell, Peter Geoffrey McLean, Erik Näslund
Tobias Rudholm, Per Mikael Hellström, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
Elvar Theodorsson, Department of Neurochemistry, Linköping University Hospital, Sweden
Colin Allan Campbell, Peter Geoffrey McLean, Neurology and GI CEDD, GlaxoSmithKline, Harlow, UK, Essex CM19 5AW, United Kingdom
Erik Näslund, Division of Surgery, Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden
Author contributions: Hellström PM, Näslund E, Campbell CA, and McLean PG contributed equally to this work; Hellström PM, Näslund E, Campbell CA, McLean PG, and Rudholm T designed research; Rudholm T performed research; Campbell CA and McLean PG contributed new reagents; Theodorsson E and Rudholm T analyzed data; Rudholm T wrote the paper.
Correspondence to: Tobias Rudholm, MSc, Gastro Centre Medicine, Karolinska University Hospital Solna, 17176 Stockholm, Sweden. tobias.rudholm@ki.se
Telephone: +46-8-51772054 Fax: +46-8-51771100
Received: March 27, 2008
Revised: June 2, 2008
Accepted: June 9, 2008
Published online: October 28, 2008
Abstract

AIM: 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).

CONCLUSION: 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.

Keywords: Gastric acid; Bravo system; Intragastric pH; Ghrelin; Somatostatin