Oxyhemoglobin-induced suppression of voltage-dependent K+ channels in cerebral arteries by enhanced tyrosine kinase activity

Masanori Ishiguro, Anthony D Morielli, Katarina Zvarova, Bruce I Tranmer, Paul L Penar, George C Wellman

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) has devastating consequences. Oxyhemoglobin (oxyhb) has been implicated in SAH-induced cerebral vasospasm as it causes cerebral artery constriction and increases tyrosine kinase activity. Voltage-dependent, Ca(2+)-selective and K(+)-selective ion channels play an important role in the regulation of cerebral artery diameter and represent potential targets of oxyhb. Here we provide novel evidence that oxyhb selectively decreases 4-aminopyridine sensitive, voltage-dependent K(+) channel (K(v)) currents by approximately 30% in myocytes isolated from rabbit cerebral arteries but did not directly alter the activity of voltage-dependent Ca(2+) channels or large conductance Ca(2+)-activated (BK) channels. A combination of tyrosine kinase inhibitors (tyrphostin AG1478, tyrphostin A23, tyrphostin A25, genistein) abolished both oxyhb-induced suppression of K(v) channel currents and oxyhb-induced constriction of isolated cerebral arteries. The K(v) channel blocker 4-aminopyridine also inhibited oxyhb-induced cerebral artery constriction. The observed oxyhb-induced decrease in K(v) channel activity could represent either channel block, or a decrease in K(v) channel density on the plasma membrane. To explore whether oxyhb altered trafficking of K(v) channels to the plasma membrane, we used an antibody generated against an extracellular epitope of K(v)1.5 channels. In the presence of oxyhb, staining of K(v)1.5 on the plasma membrane surface was markedly reduced. Furthermore, oxyhb caused a loss of spatial distinction between staining with K(v)1.5 and the general anti-phosphotyrosine antibody PY-102. We propose that oxyhb-induced suppression of K(v) currents occurs via a mechanism involving enhanced tyrosine kinase activity and channel endocytosis. This novel mechanism may contribute to oxyhb-induced cerebral artery constriction following SAH.

Original languageEnglish
JournalCirculation
Volume99
Issue number11
Pages (from-to)1252-1260
ISSN0009-7322
DOIs
Publication statusPublished - 24. Nov 2006
Externally publishedYes

Keywords

  • 4-Aminopyridine/pharmacology
  • Animals
  • Cell Membrane/metabolism
  • Cerebral Arteries/cytology
  • Electric Conductivity
  • Enzyme Inhibitors/pharmacology
  • Fluorescent Antibody Technique
  • Humans
  • Kv1.5 Potassium Channel/antagonists & inhibitors
  • Large-Conductance Calcium-Activated Potassium Channels/drug effects
  • Male
  • Muscle Cells/metabolism
  • Oxyhemoglobins/pharmacology
  • Potassium Channel Blockers/pharmacology
  • Potassium Channels, Voltage-Gated/antagonists & inhibitors
  • Protein-Tyrosine Kinases/antagonists & inhibitors
  • Rabbits
  • Staining and Labeling
  • Subarachnoid Hemorrhage/metabolism
  • Vasoconstriction/drug effects

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