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September 18, 2026Cardiovascular Research

PDE4B controls SA node automaticity via the voltage clock while PDE4D regulates the calcium clock.

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Why the study?

The role of PDE4B and PDE4D subfamily members in controlling heart rate and cardiac automaticity remains poorly defined.

Does genetic ablation of PDE4B or PDE4D alter cardiac automaticity and heart rate in mice?

Population

Pde4b knockout and Pde4d knockout mice and wild-type littermates

Comparison

Genetic ablation of Pde4b or Pde4d vs wild-type littermates

Design

Preclinical experimental study

Key result

PDE4B controls intrinsic sinoatrial node automaticity by regulating the voltage clock through the pacemaker current If, whereas PDE4D regulates the calcium clock via beta-adrenergic-induced calcium release.

Authors

WVWalma Pereira de VasconcelosPMPietro MesircaABAnne Breidenstein

Discussion

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Overview

PDE4 isoform selectivity warrants caution in cardiac drug development; leaves open translation of murine SAN mechanisms to human arrhythmias.

Key Points

  • To evaluate the specific and distinct contributions of phosphodiesterase 4B (PDE4B) and 4D (PDE4D) to cardiac automaticity and heart rate control.
  • Assayed PDE4 cAMP-hydrolytic activity and expression using radioenzymatic assays, Western blot, and RNAscope in mouse sinoatrial node tissue and pacemaker cardiomyocytes.
  • Recorded heart rate via in vivo ECG telemetry before and after autonomic nervous system blockade in wild-type, Pde4b-/-, and Pde4d-/- mice.
  • Measured ex vivo heart rate, Fluo-4 Ca2+ transients, and cellular currents (ICa,L and If) in isolated hearts and pacemaker cardiomyocytes at baseline and with isoprenaline stimulation.
  • PDE4 accounted for ~60% of cAMP hydrolysis in the sinoatrial node, with both Pde4b-/- and Pde4d-/- mice demonstrating elevated day and night heart rates relative to wild-type littermates.
  • Increased intrinsic automaticity persisted only in Pde4b-/- mice following autonomic blockade and in isolated hearts, associated with increased funny current (If) density rather than altered Ca2+ dynamics.
  • Pde4d deletion did not alter intrinsic heart rate or basal currents, but induced an increased sarcoplasmic reticulum Ca2+ leak and prolonged Ca2+ transients under β-adrenergic stimulation.

Structured PICO

Does genetic ablation of PDE4B or PDE4D alter cardiac automaticity and heart rate in mice?

P
Population
Pde4b knockout (Pde4b-/-) and Pde4d knockout (Pde4d-/-) mice and wild-type (WT) littermates
E
Exposure
Genetic ablation of Pde4b or Pde4d
C
Comparator
Wild-type (WT) littermates
O
Outcome
Heart rate (HR) and cardiac automaticity (action potential firing rate, calcium transients, funny current)surrogate

PDE4B and PDE4D have distinct roles in regulating cardiac pacemaker activity, with PDE4B controlling intrinsic automaticity via the voltage clock and PDE4D regulating the calcium clock during beta-adrenergic stimulation.

Cite This Study

Vasconcelos et al. (2026) studied Cardiac automaticity. Pde4b and Pde4d knockout vs. Wild-type littermates was evaluated on Heart rate and cardiac automaticity. PDE4B controls intrinsic sinoatrial node automaticity by regulating the voltage clock through the pacemaker current If, whereas PDE4D regulates the calcium clock via beta-adrenergic-induced calcium release.

synapsesocial.com/papers/6aacf5ed0c46fbdff987dd83https://doi.org/10.1093/cvr/cvag201
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Phosphodiesterase 4B in the cardiac L-type Ca2+ channel complex regulates Ca2+ current and protects against ventricular arrhythmias in mice2011 · 137 citations
  2. 2Phosphodiesterase 4D Regulates Baseline Sarcoplasmic Reticulum Ca <sup>2+</sup> Release and Cardiac Contractility, Independently of L-Type Ca <sup>2+</sup> Current2011 · 107 citations
  3. 3Phosphodiesterases 4B and 4D Differentially Regulate cAMP Signaling in Calcium Handling Microdomains of Mouse Hearts2024 · 11 citations
  4. 4PDE4D mediates impaired β-adrenergic receptor signalling in the sinoatrial node in mice with hypertensive heart disease2023 · 13 citations
  5. 5PDE4B mediates local feedback regulation of β1-adrenergic cAMP signaling in a sarcolemmal compartment of cardiac myocytes2014 · 39 citations