The objective of the proposed research is to gain a better understanding of what controls the metabolic rate of energy production and ciliary beating in ciliated epithelium. Of particular interest will be the mechanism of action of 5-hydroxytryptamine and dopamine which appear to be endogenous metabolic regulators with marked effects on ciliary beating in the bivalve gill. Using a combination of thin-layer chromatography, enzyme assay, radio-labeled precursor tracing, and oxygen consumption measurements, the following physiological parameters will be studied during various states of stimulation and inhibition: tissue levels of cyclic AMP, AMP, ADP, ATP, arginine, and arginine-P; the subcellular distribution and movement of calcium ion; respiratory control index and oxidative phosphorylation ratio.