Quantitative changes in gastric mucosal glycoproteins: effect of cholinergic agonist and vagal nerve stimulation in the rat.

The role of the vagus nerve and cholinergic mechanisms in the control of the rat gastric mucin and protein (PROT) release in vivo was investigated. Under urethane anaesthesia (1.25 g kg(-1)), the rats had their gastric lumen perfused with saline. Mucus secretion was measured as a function of adherent mucus on the mucosa surface and the luminal content of sialic acids (SIA), galactose (GAL), pyruvate and PROT. Electrical stimulation of the vagi significantly increased the levels of mucus (3.23 +/- 025 microg g(-1) tissue, P < 0.05), free sialic acid (FS) (0.18 +/- 0.04 mg mL(-1), P < 0.05) and PROT (0.25 +/- 0.003 mg mL(-1), P < 0.05) when compared with control animals. Bilateral cervical vagotomy had no significant effect on adherent mucus or basal levels of PROT, SIA and GAL (P > 0.05) with respect to the control. In both vagotomized and vagal intact animals, the cholinergic agonist (carbachol, 200 mg kg(-1)) significantly increased PROT, adherent mucus and FS (P < 0.05) and decreased bound sialic acid (P > 0.05). There were no visible haemorrhagic streaks on the gastric mucosa of vagotomized, vagal intact and carbachol-treated animals. The results suggest that vagus nerve does not exert a tonic control on gastric glycoprotein secretion in vivo and that cholinergic effect on the mucus secreting cells may be implemented via the intrinsic nerves of the enteric nervous system.