title: Potassium currents in isolated statocyst neurons and RPeD1 in the pond snail, Lymnaea stagnalis.
abstract: To begin to determine the underlying neural mechanisms of memory formation, we studied two different cell types that play important roles in different forms of associative learning in Lymnaea. Statocyst neurons (hair cells) mediate classical conditioning, whereas RPeD1 is a site of memory formation induced by operant conditioning of aerial respiration. Because potassium (K(+)) channels play a critical role in neuronal excitability, we initiated studies on these channels in the aforementioned neurons. Three distinct K(+) currents are expressed in the soma of both the hair cells and RPeD1. In hair cells and RPeD1, there is a fast activating and rapidly inactivating 4-aminopyridine (4-AP)-sensitive A current (I(A)), a tetraethyl ammonium (TEA)-sensitive delayed rectifying current, which exhibits slow inactivation kinetics (I(KV)), and a TEA- and 4-AP-insensitive Ca(2+)-dependent current (I(Ca-K)). In hair cells, the activation voltage of I(A); its half-maximal steady-state activation voltage and its half-maximal steady-state inactivation were at more depolarized levels than in RPeD1. The time constant of recovery from I(A) inactivation was slightly faster in hair cells. I(A) in hair cells is also smaller in amplitude than in RPeD1 and is activated at more depolarized potentials. In like manner, I(KV) is smaller in hair cells and is activated at more depolarized potentials than in RPeD1.
authors.affiliation: Laboratory of Neurobiological Engineering, Department of Biological Science and Technology, School of High-Technology for Human Welfare, Tokai University, Numazu, Shizuoka, Japan. manabu@tokai.ac.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Sakakibara
authors.forename: Futoshi
authors.initials: F
authors.lastname: Okuda
authors.forename: Kazutoku
authors.initials: K
authors.lastname: Nomura
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Hongxu
authors.initials: H
authors.lastname: Meng
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Horikoshi
authors.forename: Ken
authors.initials: K
authors.lastname: Lukowiak
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008195:Lymnaea / Q000166:cytology* / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D009474:Neurons / Q000145:classification / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology; D013997:Time Factors
chemical_list: D026902:Potassium Channel Blockers; D015221:Potassium Channels; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D002118:Calcium