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Updated: Oct 17, 2026

In vitro Assessment of Cardiac Reprogramming by Measuring Cardiac Specific Calcium Flux with a GCaMP3 Reporter
05:04

In vitro Assessment of Cardiac Reprogramming by Measuring Cardiac Specific Calcium Flux with a GCaMP3 Reporter

Published on: February 22, 2022

Regulation of cloned cardiac L-type calcium channels by cGMP-dependent protein kinase

L H Jiang1, D J Gawler, N Hodson

  • 1School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.

The Journal of Biological Chemistry
|February 29, 2000
PubMed

Insights

8-bromo-cyclic GMP (8-Br-cGMP) inhibits cardiac L-type calcium channel currents by activating protein kinase G. This inhibition occurs through phosphorylation of the alpha(1C) subunit at Serine 533.

Area of Science:

  • Cardiovascular Physiology
  • Molecular Pharmacology
  • Ion Channel Function

Background:

  • L-type calcium channels are crucial for cardiac function.
  • Cyclic GMP (cGMP) is a key second messenger involved in various cellular processes.
  • The precise role of cGMP in regulating cardiac L-type calcium channels requires further elucidation.

Purpose of the Study:

  • To investigate the effect of 8-bromo-cyclic GMP (8-Br-cGMP) on cloned cardiac L-type calcium channel currents.
  • To determine the specific site and mechanism of action of 8-Br-cGMP on these channels.

Main Methods:

  • Expression of rabbit cardiac alpha(1C) subunit, with or without beta subunits, in Xenopus oocytes.
  • Two-electrode voltage-clamp recordings to measure calcium channel currents.
  • Site-directed mutagenesis (Serine to Alanine substitutions) and application of protein kinase G inhibitor (KT5823).

Main Results:

  • 8-Br-cGMP application decreased calcium channel currents in cells expressing the alpha(1C) subunit.
  • Inhibition was blocked by the protein kinase G inhibitor KT5823.
  • Mutagenesis identified Serine 533 on the alpha(1C) subunit as the critical site for 8-Br-cGMP-mediated inhibition.

Conclusions:

  • cGMP inhibits cardiac L-type calcium channel currents.
  • This inhibition is mediated by protein kinase G.
  • Phosphorylation of the alpha(1C) subunit at Serine 533 is the key mechanism underlying cGMP's effect.

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