Aim: 

Gastric motor disorders have been reported in dystrophic (mdx) mice. In the present study we investigated the contribution of endogenous nitrergic and peptidergic components to the gastric contractile responses in strips from normal and mdx mice.

Methods: 

Gastric strips from the fundus region were mounted in organ baths for isometric recording. Electrical field stimulation (EFS) was applied via two platinum wire rings.

Results: 

In both preparations, EFS induced TTX- and atropine-sensitive excitatory responses followed, at the end of the stimulation period, by an off-relaxation. The amplitude of the contractile responses was greater in strips from mdx mice in respect to the normal ones. L-NNA increased and a-chymotrypsin decreased the amplitude of the contractile responses. a-chymotrypsin also abolished off-relaxations. The efficacy of either L-NNA or a-chymotrypsin was lower in strips from mdx mice in respect to the normal ones. a-chymotrypsin, in the presence of L-NNA, no longer decreased the amplitude of the contractile responses but still abolished off-relaxations. Muscular responses to methacholine were similar in amplitude in the two preparations.

Conclusion: 

Both endogenous nitric oxide and peptides influence the EFS-induced cholinergic responses: a stronger peptidergic modulatory action on a weaker nitrergic neurotransmission is suggested to occur in strips from mdx mice in respect to the normal ones and to contribute to the altered gastric contractile responses.