Angiotensin II upregulates K(Ca)3.1 channels and stimulates cell proliferation in rat cardiac fibroblasts

Biochem Pharmacol. 2013 May 15;85(10):1486-94. doi: 10.1016/j.bcp.2013.02.032. Epub 2013 Mar 7.


The proliferation of cardiac fibroblasts is implicated in the pathogenesis of myocardial remodeling and fibrosis. Intermediate-conductance calcium-activated K⁺ channels (K(Ca)3.1 channels) have important roles in cell proliferation. However, it is unknown whether angiotensin II (Ang II), a potent profibrotic molecule, would regulate K(Ca)3.1 channels in cardiac fibroblasts and participate in cell proliferation. In the present study, we investigated whether K(Ca)3.1 channels were regulated by Ang II, and how the channel activity mediated cell proliferation in cultured adult rat cardiac fibroblasts using electrophysiology and biochemical approaches. It was found that mRNA, protein, and current density of K(Ca)3.1 channels were greatly enhanced in cultured cardiac fibroblasts treated with 1 μM Ang II, and the effects were countered by the angiotensin type 1 receptor (AT₁R) blocker losartan, the p38-MAPK inhibitor SB203580, the ERK1/2 inhibitor PD98059, and the PI3K/Akt inhibitor LY294002. Ang II stimulated cell proliferation and the effect was antagonized by the K(Ca)3.1 blocker TRAM-34 and siRNA targeting K(Ca)3.1. In addition, Ang II-induced increase of K(Ca)3.1 expression was attenuated by transfection of activator protein-1 (AP-1) decoy oligodeoxynucleotides. These results demonstrate for the first time that Ang II stimulates cell proliferation mediated by upregulating K(Ca)3.1 channels via interacting with the AT₁R and activating AP-1 complex through ERK1/2, p38-MAPK and PI3K/Akt signaling pathways in cultured adult rat cardiac fibroblasts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology*
  • Angiotensin II Type 1 Receptor Blockers / pharmacology
  • Animals
  • Cell Proliferation / drug effects
  • Fibroblasts / cytology
  • Fibroblasts / drug effects*
  • Fibroblasts / metabolism
  • Gene Expression Regulation / drug effects
  • Heart Ventricles / cytology
  • Heart Ventricles / drug effects*
  • Heart Ventricles / metabolism
  • Intermediate-Conductance Calcium-Activated Potassium Channels / agonists
  • Intermediate-Conductance Calcium-Activated Potassium Channels / antagonists & inhibitors
  • Intermediate-Conductance Calcium-Activated Potassium Channels / genetics*
  • Intermediate-Conductance Calcium-Activated Potassium Channels / metabolism
  • Losartan / pharmacology
  • Male
  • Patch-Clamp Techniques
  • Primary Cell Culture
  • Protein Kinase Inhibitors / pharmacology
  • Pyrazoles / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Angiotensin, Type 1 / genetics
  • Receptor, Angiotensin, Type 1 / metabolism
  • Signal Transduction / drug effects
  • Transcription Factor AP-1 / antagonists & inhibitors
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism
  • Up-Regulation / drug effects
  • Vasoconstrictor Agents / pharmacology*
  • p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Angiotensin II Type 1 Receptor Blockers
  • Intermediate-Conductance Calcium-Activated Potassium Channels
  • Kcnn4 protein, rat
  • Protein Kinase Inhibitors
  • Pyrazoles
  • Receptor, Angiotensin, Type 1
  • TRAM 34
  • Transcription Factor AP-1
  • Vasoconstrictor Agents
  • Angiotensin II
  • p38 Mitogen-Activated Protein Kinases
  • Losartan