Hypoxia reduces potassium currents in cultured rat pulmonary but not mesenteric arterial myocytes

Am J Physiol. 1993 Feb;264(2 Pt 1):L116-23. doi: 10.1152/ajplung.1993.264.2.L116.


To explore possible mechanisms underlying hypoxia-induced pulmonary vasoconstriction, the effect of hypoxia on outward K+ current (Iout) was evaluated in primary cultured rat pulmonary (PA) and mesenteric (MA) arterial smooth muscle cells using the whole cell patch-clamp technique. When the cells were bathed in standard physiological salt solution and the patch pipettes contained Ca(2+)-free media with 10 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), virtually all of the Iout, including both the rapidly inactivating component (Irt) and the steady-state (noninactivating) component (Iss), was mediated by voltage-gated K+ channels. Reduction of O2 tension in the bath solution from 155 Torr to < 74 Torr with sodium dithionite reversibly inhibited both Irt and Iss in PA myocytes, but not in MA myocytes. The hypoxia-sensitive Iss was activated at about -50 mV; thus, some of the channels responsible for this current may be open at the resting membrane potential (-40 +/- 1 mV) of PA cells used in this study. Hypoxia also significantly depolarized PA cells bathed in PSS (1.8 mM Ca2+) from -40.7 +/- 1.3 to -24.0 +/- 2.4 mV, and PA cells bathed in Ca(2+)-free PSS (0.1 mM EGTA) from -38.4 +/- 1.3 to -26.1 +/- 3.9 mV. The hypoxia-induced inhibition of Iout in PA cells was accompanied by an apparent increase in inward Ca2+ current.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / pharmacology
  • Cell Hypoxia*
  • Cells, Cultured
  • Electrophysiology
  • Hypoxia / physiopathology
  • Membrane Potentials
  • Mesenteric Arteries / pathology
  • Mesenteric Arteries / physiopathology*
  • Muscle, Smooth, Vascular / pathology
  • Muscle, Smooth, Vascular / physiopathology*
  • Potassium / antagonists & inhibitors
  • Potassium / physiology*
  • Potassium Channels / physiology
  • Pulmonary Artery / pathology
  • Pulmonary Artery / physiopathology*
  • Rats


  • Potassium Channels
  • Potassium
  • Calcium