Diminished A-type potassium current and altered firing properties in presympathetic PVN neurones in renovascular hypertensive rats

Patrick M. Sonner, Jessica A. Filosa, Javier E. Stern

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Accumulating evidence supports a contribution of the hypothalamic paraventricular nucleus (PVN) to sympathoexcitation and elevated blood pressure in renovascular hypertension. However, the underlying mechanisms resulting in altered neuronal function in hypertensive rats remain largely unknown. Here, we aimed to address whether the transient outward potassium current (IA) in identified rostral ventrolateral medulla (RVLM)-projecting PVN neurones is altered in hypertensive rats, and whether such changes affected single and repetitive action potential properties and associated changes in intracellular Ca2+ levels. Patch-clamp recordings obtained from PVN-RVLM neurons showed a reduction in IA current magnitude and single channel conductance, and an enhanced steady-state current inactivation in hypertensive rats. Morphometric reconstructions of intracellularly labelled PVN-RVLM neurons showed a diminished dendritic surface area in hypertensive rats. Consistent with a diminished IA availability, action potentials in PVN-RVLM neurons in hypertensive rats were broader, decayed more slowly, and were less sensitive to the K2+ channel blocker 4-aminopyridine. Simultaneous patch clamp recordings and confocal Ca2+ imaging demonstrated enhanced action potential-evoked intracellular Ca+ transients in hypertensive rats. Finally, spike broadening during repetitive firing discharge was enhanced in PVN-RVLM neurons from hypertensive rats. Altogether, our results indicate that diminished IA availability constitutes a contributing mechanism underlying aberrant central neuronal function in renovascular hypertension.

Original languageEnglish (US)
Pages (from-to)1605-1622
Number of pages18
JournalJournal of Physiology
Volume586
Issue number6
DOIs
StatePublished - Mar 15 2008

ASJC Scopus subject areas

  • Physiology

Fingerprint Dive into the research topics of 'Diminished A-type potassium current and altered firing properties in presympathetic PVN neurones in renovascular hypertensive rats'. Together they form a unique fingerprint.

Cite this