Differences in potential and content of the mucus in the stomach of the rat with avitaminosis A

Vitamin A (vit. A) acts in the synthesis of glycoproteins and in cell surface phenomena of epithelia. Since the glycoproteins of gastric mucus and the integrity of gastric cell membranes are components of gastric barrier (GB), vit. A could play a role in GB. Five groups of rats were used: I) rats fed on vit. A deficient diet; II) rats pair-fed plus a daily oral dose of 45 micrograms vit. A; III) normal rats; IV) rats recovered from avitaminosis A (avit. A) after 20 days of daily oral dose of 300 micrograms vit. A; V) rats pair-fed plus a daily oral dose of 45 micrograms vit. A. We measured: 1) transparietal gastric potential difference (PD) in vivo (by means of agar-KCl electrodes); 2) mucus (by binding of Alcian blue): in gastric mucosa; adherent to gastric mucosa; in gastric lumen; 3) dry weight of the stomach. Avit. A induced: i) a decrease of PD and mucus in mucosa and lumen; ii) an increase of mucus adherent to mucosa; iii) an increase of the percentage of dry weight on wet weight. All parameters were normal after recovery from avit. A. Results suggest that avit. A could reduce either mucus synthesis or its erosion. Moreover avit. A might modify mucus structure and sterical configuration of mucosal cells. The alteration of mucosal cell membranes could decrease PD. In conclusion the modifications of some components of rat GB seem specifically caused by avit. A and suggest a protective role of vit. A.