Role of NAD(P)H oxidase in the regulation of cardiac L-type Ca2+ channel function during acute hypoxia

Cardiovasc Res. 2005 Sep 1;67(4):624-35. doi: 10.1016/j.cardiores.2005.04.025.


Objective: The role of NAD(P)H oxidase in regulating cellular production of reactive oxygen species (ROS) and the L-type Ca2+ channel during acute hypoxia was examined in adult ventricular myocytes from guinea pig.

Methods: The fluorescent indicator dihydroethidium (DHE) was used to detect superoxide and the response of the L-type Ca2+ channel to beta-adrenergic receptor stimulation was used as a functional reporter since hypoxia increases the sensitivity of the L-type Ca2+ channel (I(Ca-L)) to isoproterenol (Iso).

Results: Hypoxia caused a 41.2+/-5.2% decrease in the rate of the DHE signal (n=21; p<0.01). Of the classical NAD(P)H oxidase inhibitors, DPI but not apocynin mimicked the effect of hypoxia on the sensitivity of I(Ca-L) to Iso. However, the potent NAD(P)H oxidase agonist angiotensin II had no effect on cellular superoxide or the sensitivity of I(Ca-L) to Iso. Although DPI inhibits NAD(P)H oxidase, it also decreased superoxide in isolated mitochondria in a concentration-dependent manner. Partial inhibition of mitochondrial function with nanomolar concentrations of FCCP or myxothiazol mimicked the effect of hypoxia on cellular superoxide and the sensitivity of I(Ca-L) to Iso. In addition, hypoxia caused a 69.3+/-0.8% decrease in superoxide in isolated mitochondria (n=4; p<0.01), providing direct evidence for a role for the mitochondria.

Conclusions: Our data suggest that mitochondria appear to be involved in oxygen sensing, regulation of cellular ROS, and the function of I(Ca-L) during acute hypoxia in cardiac myocytes and NAD(P)H oxidase does not appear to contribute substantially.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology
  • Animals
  • Calcium Channels, L-Type / metabolism*
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / pharmacology
  • Cell Hypoxia
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Guinea Pigs
  • Hydrogen Peroxide / analysis
  • Hydrogen Peroxide / metabolism
  • Ionophores / pharmacology
  • Methacrylates / pharmacology
  • Microscopy, Fluorescence
  • Mitochondria, Heart / chemistry
  • Mitochondria, Heart / drug effects
  • Mitochondria, Heart / metabolism*
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / ultrastructure
  • NADPH Oxidases / antagonists & inhibitors
  • NADPH Oxidases / physiology*
  • Onium Compounds / pharmacology
  • Reactive Oxygen Species / analysis
  • Reactive Oxygen Species / metabolism*
  • Spectrometry, Fluorescence
  • Superoxides / analysis
  • Superoxides / metabolism
  • Thiazoles / pharmacology


  • Calcium Channels, L-Type
  • Ionophores
  • Methacrylates
  • Onium Compounds
  • Reactive Oxygen Species
  • Thiazoles
  • Superoxides
  • Angiotensin II
  • Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
  • diphenyleneiodonium
  • myxothiazol
  • Hydrogen Peroxide
  • NADPH Oxidases