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Updated: May 22, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
10:53

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Published on: July 3, 2013

The inhibitory effect of BIM (I) on L-type Ca²⁺ channels in rat ventricular cells

Youn Kyoung Son1, Da Hye Hong, Tae-Hoon Choi

  • 1Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Republic of Korea.

Biochemical and Biophysical Research Communications
|May 29, 2012
PubMed

Insights

Bisindolylmaleimide I (BIM (I)), a protein kinase C inhibitor, directly inhibits L-type Ca(2+) channels in rat heart cells. This effect is independent of protein kinase C signaling, suggesting caution when using BIM (I) for ion channel studies.

Area of Science:

  • Cardiovascular Physiology
  • Molecular Pharmacology
  • Ion Channel Biology

Background:

  • Protein kinase C (PKC) plays a role in regulating cardiac function.
  • Bisindolylmaleimide I (BIM (I)) is a commonly used inhibitor of PKC.
  • The direct effects of BIM (I) on cardiac ion channels are not fully understood.

Purpose of the Study:

  • To investigate the direct effect of BIM (I) on L-type Ca(2+) channels in rat ventricular myocytes.
  • To determine if the inhibitory effect of BIM (I) on L-type Ca(2+) channels is mediated by PKC.

Main Methods:

  • Electrophysiological recordings (whole-cell patch-clamp) were used to measure L-type Ca(2+) current.
  • Concentration-dependent inhibition by BIM (I) was assessed.
  • Effects on steady-state activation and inactivation curves were analyzed.
  • Other PKC inhibitors (PKC-IP, chelerythrine) were used to probe the involvement of PKC.

Main Results:

  • BIM (I) inhibited L-type Ca(2+) current in a concentration-dependent manner (K(d) = 3.31 ± 0.25 μM).
  • Inhibition by BIM (I) altered the steady-state inactivation curve but not the activation curve.
  • Other PKC inhibitors did not affect L-type Ca(2+) current or BIM (I) inhibition.
  • The inhibitory effect of BIM (I) on L-type Ca(2+) current was independent of PKC.

Conclusions:

  • BIM (I) directly inhibits L-type Ca(2+) channels in rat ventricular myocytes.
  • The inhibitory action of BIM (I) on these channels is not mediated through the PKC pathway.
  • Findings necessitate careful consideration in studies utilizing BIM (I) for PKC inhibition and ion channel modulation research.

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