Ionophore-mediated calcium control of ciliary arrest in the fingernail clam, Musculium transversum

Abstract

1. 1. Lateral cilia on the gill of the fingernail clam, Musculium transversum, normally beats with a metachronal rhythm. 2. 2. The metachronal rhythm is maintained in the presence of 10.0 mM calcium chloride (CaCl 2), 15 mM potassium chloride (KCl) or 15 mM NaCl. 3. 3. Lateral ciliary arrest occurred when the gill perfusion contained 10 mM CaCl 2 and 10 −5 M (small clams) or 10 −6 M (large clams) A23187 (a calcium ionophore). 4. 4. Lateral ciliary arrest is not produced in either CaCl 2 or ionophore and monovalent cations alone. 5. 5. Restoration of the metachronal rhythm results with superfusion of lateral cilia in KCl, CaCl 2 or NaCl alone. 6. 6. These data show the important role that intracellular Ca 2 + concentration has on the behavior of lateral cilia. The physiological significance seems to be the momentary or complete shut down of water currents under unfavorable environmental conditions.