Possible involvement of nitric oxide in coordination of buccal rhythm and gut motility in Lymnaea stagnalis.

NO-generating drugs (SNP, SNAP, NaNO2) activated the standard buccal rhythm and simultaneously slowed down the endogenous rhythm of the NO-synthesizing neuron B2 which enhances gut motility. In the B2, these drugs caused giant hyperpolarizing waves strongly associated with the buccal cycles. Hyperpolarizing waves on the B2 could also be induced by prolonged stimulation of the B2. The inhibitor of NO-synthase L-NNA or the NO scavanger PTIO abolished giant hyperpolarizing waves, depolarised the B2 and activated fast bursting in the B2. The results suggest that NO may be involved in coordination of radula and foregut movements.