Differential oxygen sensitivity of calcium channels in rabbit smooth muscle cells of conduit and resistance pulmonary arteries

J Physiol. 1996 Mar 1;491 ( Pt 2)(Pt 2):511-8. doi: 10.1113/jphysiol.1996.sp021235.


1. Calcium currents were recorded from smooth muscle cells dispersed from conduit and resistance rabbit pulmonary arteries. We tested the hypothesis that Ca2+ channel activity was regulated by environmental O2 tension. 2. Conduit (proximal) and resistance (distal) myocytes differ in their Ca2+ channel density and responses to low PO2. Ca2+ current density in distal myocytes (20.7 +/- 7.4 pA pF-1, n = 10) is almost twice the value in proximal myocytes (12.6 +/- 5.5 pA pF-1, n = 39). In proximal myocytes, the predominant response to reductions in PO2 is inhibition of the calcium current (n = 12) at membrane potentials below 0 mV, whereas potentiation of current amplitude is observed in distal myocytes (n = 24). 3. Hypoxia also produces opposite shifts in the conductance-voltage relationships along the voltage axis. The average displacements induced by low PO2 are +5.05 +/- 2.98 mV (n = 5) in proximal myocytes and -6.06 +/- 2.45 (n = 10) in distal myocytes. 4. These findings demonstrate longitudinal differences in Ca2+ channel density and O2 sensitivity in myocytes along the pulmonary arterial tree. These results may help to understand the differential reactivity to hypoxia of the pulmonary vasculature: vasodilatation in conduit arteries and vasoconstriction in resistance vessels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels / drug effects*
  • Calcium Channels / physiology
  • Hypoxia / physiopathology
  • Male
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Muscle, Smooth, Vascular / drug effects*
  • Muscle, Smooth, Vascular / physiology
  • Oxygen / pharmacology*
  • Pulmonary Artery / drug effects*
  • Rabbits


  • Calcium Channels
  • Oxygen