P3.76 Saturday, Jan. 5 The effect of the hyperpolarization-activated inward current antagonist, ZD7288, on the locomotor rhythm of Clione limacina WILLINGHAM, K.A.*; WALTON, D.B.; PIRTLE, T.J.; SATTERLIE, R.A.; Abilene Christian University; Abilene Christian University; Abilene Christian University; University of North Carolina, Wilmington Thomas.Pirtle@acu.edu
The pteropod mollusk, Clione limacina, swims by producing rhythmic movements of its wing-like parapodia. A network of swim interneurons in the pedal ganglia of Clione forms a central pattern generator that ultimately produces this swim rhythm. Cellular and network properties of the Clione swim central pattern generator are modified to produce behaviorally relevant acceleration of swimming, and in this study we show that one cellular property intrinsic to swim interneurons, the hyperpolarization-activated cation current (Ih) that underlies a sag potential in swim interneurons, contributes to locomotor rhythm production. Previously, the Ih antagonist, ZD7288 was shown to inhibit serotonin induced acceleration in Clione. In addition ZD7288 was also shown to inhibit the sag potential and increase the time of onset of postinhibitory rebound (PIR) in swim interneurons. Here we show that ZD7288 (200 micromolar), when administered in the absence of serotonin, significantly reduces fictive slow swim activity recorded intracellularly from swim interneurons. We also show that there is a significant negative correlation between the sag potential and the latency to PIR. Our data indicate that Ih operates in the normal voltage range of swim interneurons during slow swim activity and contributes to locomotor rhythm generation in Clione.