Gastric epithelial cell proliferation and histological damage after hypertonic sodium chloride: the effect of variation in the strain of rat.

Two strains of rat, Sprague-Dawley and inbred Piebald Virol Glaxo pigmented (PVG) strain, were dosed orally with hypertonic sodium chloride at a dose of 0.25, 0.5, 1.0 or 1.33 g/kg. Gastric epithelial cell proliferation was compared 16 hours after a single dose. The rats were given intraperitoneal bromodeoxyuridine (20 mg/kg) 1 hour before sacrifice, and cells undergoing DNA synthesis (S-phase) were assessed using a monoclonal antibody to bromodeoxyuridine. The number of labelled cells per gastric gland was counted using video image analysis, assessing ten low-power fields (160-180 gastric glands) per rat. Tissue injury was graded for submucosal oedema, inflammation and necrosis; it was minimal after dosing with 0.25 and 0.5 g/kg of sodium chloride. The PVG rats were more susceptible to tissue injury after dosing with 1.0 or 1.33 g/kg of sodium chloride: submucosal oedema, 80% in the PVG and 10% in the Sprague-Dawley; inflammation, 70% compared with 10%; necrosis, 70% compared with 20%. The number of labelled cells per fundic gland increased with increasing dose concentration of sodium chloride and the response was similar for both strains of rat. Plasma gastrin concentration at the time of sacrifice was significantly higher in the PVG rat for the 0.5, 1.0 and 1.33 g/kg doses. These strain differences may be useful in the further evaluation of the mechanisms of sodium chloride-induced tissue damage and repair.