Inhibition of hypoxic pulmonary vasoconstriction by antagonists of store-operated Ca2+ and nonselective cation channels

Letitia Weigand, Joshua Foxson, Jian Wang, Larissa Shimoda, J. T. Sylvester

Research output: Contribution to journalArticle

Abstract

Previous studies indicated that acute hypoxia increased intracellular Ca2+ concentration ([Ca2+]i), Ca2+ influx, and capacitative Ca2+ entry (CCE) through store-operated Ca2+ channels (SOCC) in smooth muscle cells from distal pulmonary arteries (PASMC). which are thought to be a major locus of hypoxic pulmonary vasoconstriction (HPV). Moreover, these effects were blocked by Ca 2+-free conditions and antagonists of SOCC and nonselective cation channels (NSCC). To test the hypothesis that in vivo HPV requires CCE, we measured the effects of SOCC/NSCC antagonists (SKF-96365, NiCl2, and LaCl3) on pulmonary arterial pressor responses to 2% O2 and high-KCl concentrations in isolated rat lungs. At concentrations that blocked CCE and [Ca2+]i responses to hypoxia in PASMC. SKF-96365 and NiCl2 prevented and reversed HPV but did not alter pressor responses to KCl. At 10 μM, LaCl3 had similar effects, but higher concentrations (30 and 100 μM) caused vasoconstriction during normoxia and potentiated HPV, indicating actions other than SOCC blockade. Ca2+-free perfusate and the voltage-operated Ca2+ channel (VOCC) antagonist nifedipine were potent inhibitors of pressor responses to both hypoxia and KCl. We conclude that HPV required influx of Ca2+ through both SOCC and VOCC. This dual requirement and virtual abolition of HPV by either SOCC or VOCC antagonists suggests that neither channel provided enough Ca2+ on its own to trigger PASMC contraction and/or that during hypoxia, SOCC-dependent depolarization caused secondary activation of VOCC.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume289
Issue number1 33-1
DOIs
StatePublished - Jul 2005

Fingerprint

Vasoconstriction
Cations
Lung
1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
Nifedipine
Pulmonary Artery
Smooth Muscle Myocytes
Hypoxia

Keywords

  • Angiotensin II
  • Calcium channels
  • Calcium signaling
  • Isolated rat lung
  • Pulmonary vascular resistance
  • Vascular smooth muscle

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Cell Biology
  • Physiology

Cite this

Inhibition of hypoxic pulmonary vasoconstriction by antagonists of store-operated Ca2+ and nonselective cation channels. / Weigand, Letitia; Foxson, Joshua; Wang, Jian; Shimoda, Larissa; Sylvester, J. T.

In: American Journal of Physiology - Lung Cellular and Molecular Physiology, Vol. 289, No. 1 33-1, 07.2005.

Research output: Contribution to journalArticle

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