Expression of neuronal nitric oxide synthase in rabbit carotid body glomus cells regulates large-conductance Ca2+-activated potassium currents

J Neurophysiol. 2010 Jun;103(6):3027-33. doi: 10.1152/jn.01138.2009. Epub 2010 Mar 31.

Abstract

Our previous studies show that a decrease in endogenous nitric oxide (NO) is involved in the blunted outward K(+) currents in carotid body (CB) glomus cells from chronic heart failure (CHF) rabbits. In the present study, we measured the effects of the neuronal nitric oxide synthase (nNOS) transgene on the K(+) currents in CB glomus cells from pacing-induced CHF rabbits. Using single-cell real-time RT-PCR and immunofluorescent techniques, we found that nNOS mRNA and protein are expressed in the rabbit CB glomus cells and CHF decreased the expression of nNOS mRNA and protein in CB glomus cells. After 3 days of an adenoviral nNOS (Ad.nNOS) gene transfection, the expression of nNOS protein was increased to the level found in sham CB glomus cells. In whole cell patch-clamp experiments, Ad.nNOS markedly reversed the attenuated K(+) currents in CB glomus cells from CHF rabbits. The specific nNOS inhibitor (S-methyl-l-thiocitrulline [SMTC]) and large-conductance Ca(2+)-activated K(+) (BK) channel blocker (iberiotoxin) fully abolished the effect of Ad.nNOS on the K(+) currents in the CB glomus cells from CHF rabbits. However, neither CHF nor Ad.nNOS altered the protein expression of BK channel alpha-subunit. These results suggest that a decrease of NO induced by an attenuated nNOS activity lowers the activation of the BK channels but not the protein expression of the BK channel alpha-subunit in the CB glomus cells during CHF.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Analysis of Variance
  • Animals
  • Body Weight / physiology
  • Calcium / metabolism
  • Carotid Body / pathology*
  • Chemoreceptor Cells / metabolism*
  • Citrulline / analogs & derivatives
  • Citrulline / pharmacology
  • Disease Models, Animal
  • Enzyme Inhibitors / pharmacology
  • Genetic Vectors / physiology
  • Green Fluorescent Proteins / genetics
  • Heart Failure / pathology*
  • Large-Conductance Calcium-Activated Potassium Channels / physiology*
  • Male
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Nitric Oxide Synthase Type I / genetics
  • Nitric Oxide Synthase Type I / metabolism*
  • Pacemaker, Artificial
  • Patch-Clamp Techniques / methods
  • Peptides / pharmacology
  • Potassium Channel Blockers / pharmacology
  • RNA, Messenger / metabolism
  • Rabbits
  • Thiourea / analogs & derivatives
  • Thiourea / pharmacology
  • Transduction, Genetic / methods
  • Tyrosine 3-Monooxygenase / metabolism

Substances

  • Enzyme Inhibitors
  • Large-Conductance Calcium-Activated Potassium Channels
  • Peptides
  • Potassium Channel Blockers
  • RNA, Messenger
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Citrulline
  • iberiotoxin
  • Nitric Oxide Synthase Type I
  • Tyrosine 3-Monooxygenase
  • Thiourea
  • S-methylthiocitrulline
  • Calcium