Absence of tachyphylaxis in gastric acid secretion during pentagastrin infusion
Chin, T.W.; MacLeod, S.M.; Mahon, W.A.
Journal of Clinical Pharmacology 26(4): 281-285
ISSN/ISBN: 0091-2700 PMID: 3084597 DOI: 10.1002/j.1552-4604.1986.tb03524.x
Tachyphylaxis to stimulation of gastric juice secretion during intravenous pentagastrin (PG) infusion has been reported in animal studies. We assessed the course of gastric response to PG 2 .mu.g/kg/hr over eight hours in eight healthy subjects. Peak H+, pepsin, and volume secretions occurred during the second half hour of stimulation. Peak H+ output was 11.6 .+-. 1.3 mmol/0.5 hr or 7.6 .+-. 0.8% of the total eight-hour secretion. During subsequent half-hour collection intervals, there was no significant decline in response, and the average output was 10.3 .+-. 0.4 mmol/0.5 hr (6.5 .+-. 0.1%). Peak pepsin and volume secretions were respectively 10.0 .+-. 1.4% (74.8 .+-. 11.6 mg/0.5 hr) and 8.8 .+-. 1.1% (146.3 .+-. 17.4 mL/0.5 hr) of the total eight-hour secretion. Although there was a significant decline in pepsin and volume response subsequent to the peak output, the decline was not continuous, and pepsin and volume secretions were maintained, respectively, at 6.0 < 0.2% (46.1 .+-. 2.5 mg/0.5 hr) and 6.2 .+-. 0.1% (107.5 .+-. 3.0 ml/0.5 hr) of the total eight-hour secretion. Our study did not demonstrate any tachyphylaxis in H+ response to continuous PG stimulation. This model appears to be a valid tool for the assessment of histamine-H2 antagonist effects on stimulated gastric juice secretion over 8 hours in humans.