HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 98/5/2612    most recent 00599.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Teruyama, R. Articles by Armstrong, W. E. Search for Related Content PubMed PubMed Citation Articles by Teruyama, R. Articles by Armstrong, W. E.

Calcium-Dependent Fast Depolarizing Afterpotentials in Vasopressin Neurons in the Rat Supraoptic Nucleus

Department of Anatomy and Neurobiology, University of Tennessee, Health Science Center, Tennessee

Submitted 25 May 2007; accepted in final form 16 August 2007

Oxytocin (OT) and vasopressin (VP) synthesizing magnocellular cells (MNCs) in the supraoptic nucleus (SON) display distinct firing patterns during the physiological demands for these hormones. Depolarizing afterpotentials (DAPs) in these neurons are involved in controlling phasic bursting in VP neurons. Our whole cell recordings demonstrated a Cs⁺-resistant fast DAP (fDAP; decay tau = 200 ms), which has not been previously reported, in addition to the well-known Cs⁺-sensitive slower DAP (sDAP; decay tau = 2 s). Immunoidentification of recorded neurons revealed that all VP neurons, but only 20% of OT neurons, expressed the fDAP. The activation of the fDAP required influx of Ca²⁺ through voltage-gated Ca²⁺ channels as it was strongly suppressed in Ca²⁺-free extracellular solution or by bath application of Cd²⁺. Additionally, the current underlying the fDAP (I_fDAP) is a Ca²⁺-activated current rather than a Ca²⁺ current per se as it was abolished by strongly buffering intracellular Ca²⁺ with BAPTA. The I-V relationship of the I_fDAP was linear at potentials less than –60 mV but showed pronounced outward rectification near –50 mV. I_fDAP is sensitive to changes in extracellular Na⁺ and K⁺ but not Cl^–. A blocker of Ca²⁺-activated nonselective cation (CAN) currents, flufenamic acid, blocked the fDAP, suggesting the involvement of a CAN current in the generation of fDAP in VP neurons. We speculate that the two DAPs have different roles in generating after burst discharges and could play important roles in determining the distinct firing properties of VP neurons in the SON neurons.

This article has been cited by other articles:

				Q.-H. Chen and G. M. Toney Excitability of paraventricular nucleus neurones that project to the rostral ventrolateral medulla is regulated by small-conductance Ca2+-activated K+ channels J. Physiol., September 1, 2009; 587(17): 4235 - 4247. [Abstract] [Full Text] [PDF]

				X. Liu, K. Lee, and A. E. Herbison Kisspeptin Excites Gonadotropin-Releasing Hormone Neurons through a Phospholipase C/Calcium-Dependent Pathway Regulating Multiple Ion Channels Endocrinology, September 1, 2008; 149(9): 4605 - 4614. [Abstract] [Full Text] [PDF]