Effect of inhibition of acid secretion on the regulatory peptides in the rat stomach.

The effect of inhibiting acid secretion by pharmacologic agents on the gastric content of regulatory peptides has been determined by radioimmunoassay and immunocytochemistry. Plasma, antral, and fundic concentrations of gastrin were elevated in rats rendered virtually achlorhydric by treatment with high-dose omeprazole (400 mumol/kg daily for 10 wk). This was associated with an increase in the number and staining intensity of gastrin immunoreactive cells. A clear reciprocal relationship was observed between antral gastrin and somatostatin as assessed by both quantitative and qualitative methods. These changes had disappeared 10 wk after treatment was stopped. No alteration was found in the concentrations of other regulatory peptides proposed as important in control of acid secretion. Plasma and antral gastrin concentrations were elevated in rats treated with high-dose ranitidine (700 mumol/kg daily), but to a lesser extent than during omeprazole therapy, and somatostatin concentrations were unchanged.