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

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Stern, J E Articles by Armstrong, W E Search for Related Content PubMed PubMed Citation Articles by Stern, J E Articles by Armstrong, W E

Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis 38163, USA. javier@nb.utmem.edu

1. Intracellular recordings were obtained in vitro from oxytocin and vasopressin neurones from dioestrous and lactating female rats. Oxytocin neurones were characterized under current clamp by the expression of a depolarization-activated, sustained outward rectification (SOR) and a rebound depolarization (RD). 2. An increment in extracellular K+ shifted the expression of the SOR and RD towards a more depolarized membrane potential, indicating that the mechanisms underlying these events are dependent on extracellular potassium. 3. The SOR and RD were blocked by external tetraethylammonium (10 mM) and Ba2+ (0.1-0.5 mM). Cs+ (2 mM) blocked the hyperpolarization-activated inward rectification without affecting the expression of the SOR and RD. 4. The SOR was not affected by 4-aminopyridine (6 mM). However, the rebound amplitude was significantly enhanced, indicating that the activation of a transient outward current interacts with the expression of the rebound. 5. Iberiotoxin (100 nM) and apamin (50 nM), toxins known to block some calcium-dependent potassium conductances, did not affect the expression of the SOR and RD. 6. The SOR and RD were significantly reduced by Cd2+ (0.5 mM) but not by Ni2+ (0.25 mM). 7. Muscarine (10 microM) did not affect the SOR or the RD. 8. These results indicate that the SOR and RD depend upon a depolarization-activated, sustained outward potassium current, which might be calcium dependent. A current with these characteristics has never been described before in the magnocellular system. Voltage-clamp experiments are needed to completely characterize this potassium conductance selectively expressed by oxytocin neurones.