| pubmed-article:41632 | pubmed:abstractText | Isolated pinnules of the gill of Aplysia contract when dopamine (DA) is perfused through the bath. The contraction is not blocked by high-Mg2+ seawater, and reflects excitatory receptors for DA on the smooth muscle cells of the gill. The pinnule often shows irregular, spontaneous contractions which are blocked by high-Mg2+ seawater and 30 mM CoCl2. These contractions reflect spontaneous activity of a peripheral nerve plexus. No other transmitter was found to be directly excitatory on the muscle fibers, although there are inhibitory receptors for serotonin (5-HT). Tactile stimulation of the pinnule evoked a two-component contractile reflex contraction due to activation of the peripheral nerve plexus. Acetylcholine, octopamine, and 5-HT but not several other transmitters depressed these responses, presumably due to inhibitory receptors on the neurons of the peripheral plexus. | lld:pubmed |
