Sustained outward rectification of oxytocinergic neurones in the rat supraoptic nucleus

Ionic dependence and pharmacology

Javier E. Stern, William Armstrong

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

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 μM) 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.

Original languageEnglish (US)
Pages (from-to)497-508
Number of pages12
JournalJournal of Physiology
Volume500
Issue number2
DOIs
StatePublished - Apr 15 1997

Fingerprint

Supraoptic Nucleus
Potassium
Oxytocin
Pharmacology
Neurons
Muscarine
Calcium
Apamin
4-Aminopyridine
Tetraethylammonium
Vasopressins
Membrane Potentials

All Science Journal Classification (ASJC) codes

  • Physiology

Cite this

Sustained outward rectification of oxytocinergic neurones in the rat supraoptic nucleus : Ionic dependence and pharmacology. / Stern, Javier E.; Armstrong, William.

In: Journal of Physiology, Vol. 500, No. 2, 15.04.1997, p. 497-508.

Research output: Contribution to journalArticle

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