title: Neurotransmitter receptors on gill muscle fibers and the gill peripheral nerve plexus in Aplysia.
abstract: 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.
mesh_terms: D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D005880:Gills / Q000294:innervation / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism* / Q000494:pharmacology; D009655:Octopamine / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012623:Seawater
chemical_list: D018377:Neurotransmitter Agents; D011956:Receptors, Cell Surface; D009655:Octopamine