Quinine Stimulates Gastric Acid Secretion in Rats

Abstract

Quinine remains an important anti-malarial drug. However, the effects of quinine on many gastrointestinal functions are not known. This study was aimed at investigating the effect of quinine on gastric acid secretion, which might be important in peptic ulcer patients. Forty albino Wistar rats were randomly divided in 8 groups. Gastric acid output was measured by the continuous perfusion method in animals anaesthetized with urethane (6ml/100g). After consistent basal gastric output were obtained, the animals were treated as follows: group 1, normal saline (1ml/kg); group 2, quinine (10mg/kg); group 3, carbachol (50μg/kg); group 4, quinine + carbachol; group 5, atropine (1mg/kg) + quinine; group 6, histamine (20mg/kg); group 7, quinine + histamine and group 8, ranitidine (4mg/kg) + quinine. Values were expressed as mean ± SEM and compared by student t-test. Result showed that peak acid secretion (PAS) in rats treated with normal saline was 1.26 ± 0.04mEq/L/10min. Quinine significantly increased PAS to 2.00 ± 0.18mEq/L/10min (p < 0.01). Injection of quinine before carbachol did not affect the PAS as compared with carbachol alone (p > 0.05) and atropine administration did not reduce the PAS to quinine (p> 0.05). Histamine significantly increased the PAS to 8.08 ± 0.26mEq/L/10min (p <0.001). Injection of quinine before histamine significantly reduced the PAS to 3.42 ± 1.12mEq/L/10min (p < 0.01) and ranitidine blocked the secretory response of the stomach to quinine. In conclusion, quinine increased gastric acid secretion in rats by stimulating histamine H2 receptors.