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Related Concept Videos

Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
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The regulation of sodium and potassium ion concentrations in the human body is a complex process governed primarily by hormones such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Sodium Regulation
Sodium ions make up approximately 90% of extracellular cations, with a normal blood plasma concentration of 136–148 mEq/L. A decrease in blood volume and pressure triggers the release of renin from granular cells in the juxtaglomerular complex (JGC), primarily in...
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The Role of Ion Channels in Neuronal Computation

A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
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Feedback Regulation of Calcium Concentration01:27

Feedback Regulation of Calcium Concentration

Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
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Voltage-gated Ion Channels01:26

Voltage-gated Ion Channels

Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
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Non-gated Ion Channels01:24

Non-gated Ion Channels

Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
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Ca/calmodulin kinase II differentially modulates potassium currents.

Stefan Wagner1, Elena Hacker, Eleonora Grandi

  • 1Department of Cardiology and Pneumology, Georg-August-University Göttingen, Göttingen, Germany.

Circulation. Arrhythmia and Electrophysiology
|October 8, 2009
PubMed
Summary

Calcium-calmodulin-dependent protein kinase II (CaMKII) affects potassium currents (I(to) and I(K1)) through acute regulation and chronic expression changes, impacting action potential duration (APD) differently in rabbits and mice.

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Published on: November 11, 2022

Area of Science:

  • Cardiovascular Physiology
  • Molecular Cardiology
  • Cardiac Electrophysiology

Background:

  • Potassium currents are crucial for cardiac action potential duration (APD) and preventing arrhythmias.
  • Upregulated Ca/calmodulin-dependent protein kinase II (CaMKII) in heart failure can modify ion channel function and expression.

Purpose of the Study:

  • To investigate the impact of CaMKII overexpression on key potassium currents (I(to) and I(K1)) and their underlying channel proteins.
  • To differentiate between acute regulatory effects and chronic expression changes induced by CaMKII.

Main Methods:

  • Adenoviral gene transfer in rabbit ventricular myocytes for acute CaMKII overexpression.
  • Utilizing CaMKIIδ(C)-transgenic mice for chronic overexpression studies.
  • Electrophysiological recordings of I(to) and I(K1), Western blotting for channel proteins, and computational modeling.

Main Results:

  • CaMKII overexpression increased I(to,slow) and K(V)1.4 expression, while chronic overexpression decreased I(to,fast), K(V)4.2, and KChIP2.
  • CaMKII acutely accelerated I(to) recovery from inactivation, an effect reversed by CaMKII inhibition.
  • I(K1) and Kir2.1 mRNA were downregulated by CaMKII, but CaMKII acutely increased I(K1) activity.
  • APD was prolonged in mice and shortened in rabbits, reflecting differential current modulation.

Conclusions:

  • CaMKII exerts both rapid, activity-dependent effects and slower, expression-dependent effects on cardiac potassium currents.
  • These dual actions of CaMKII on I(to) and I(K1) lead to complex, model-specific alterations in APD and potential arrhythmogenesis.