Comparative effects of neurotransmitters and calcium blockers onisolated gills and whole animals of the mussel, Mytilus edulis

摘要

It is generally accepted that the lateral cilia of bivalve molluscs are inhibited by dopaminergic systems and excited by serotonergic systems. Most of this experimentation has been carried out on excised gills of the mussel, Mytilus edulis and not on whole animals. We conducted preliminary tests to compare the effects of the neurotransmitters serotonin (5 HT), dopamine (DA), and apomor-phine and the calcium channel blocker lanthanum on pumping activity of intact M. edulis and the ciliary activity of isolated gill tissue. We also exposed isolated gill filaments to the calcium channel blockers cobalt chloride and verapamil. Whole animals and freshly excised gill sections were kept in filtered seawater at ambient temperature ( similar to 20 degree C). Experimental drug was added directly to the bath water. Activity of the lateral cilia of isolated gills was monitored with an inverted compound microscope. Water processing rates of whole animals were examined using particle image velocimetry (PIV). Lanthanum induced shedding of the gill epi-thelia in excised sections and in whole animals obviating any effect on the lateral cilia. Cobalt chloride, DA, and verapamil had no effect on gill sections. When exposed to 1 x 10 super(-6) M apomor-phine, 30% of gill sections showed some inhibition; 50% were inhibited at 1 x 10 super(-5) M. In the whole animal, 1 x 10 super(-6) M apomorphine had a significant negative effect on velocities of particles in the excurrent flow. 5 HT appeared to increase synchrony (metachronism) of the lateral ciliary beat in isolated gill sections. Preliminary work suggests that neural agents affect whole animals differently than isolated gill tissue.