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Updated: Jul 4, 2026
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Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice
Published on: July 5, 2021
Spontaneous frequency of rabbit atrioventricular node myocytes depends on SR function
J M Ridley1, H Cheng, O J Harrison
1Department of Physiology & Pharmacology, Cardiovascular Research Laboratories, Bristol Heart Institute, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
Cell Calcium
|June 14, 2008
Summary
Researchers studied intracellular calcium handling in the atrioventricular node (AVN). They found that calcium cycling is linked to spontaneous electrical activity in AVN cells, providing new insights into cardiac pacemaking.
Area of Science:
- Cardiology
- Cell Physiology
- Biophysics
Background:
- Spontaneous calcium release from the sarcoplasmic reticulum (SR) is crucial for sinoatrial node pacemaking.
- The role of intracellular calcium in the atrioventricular node (AVN) remains less understood.
Purpose of the Study:
- To investigate intracellular calcium handling in isolated rabbit AVN cells.
- To elucidate the link between cellular calcium cycling and spontaneous activity in the AVN.
Main Methods:
- Monitoring intracellular calcium using fluo-3 and confocal microscopy in rabbit AVN cells.
- Assessing the effects of ryanodine, isoprenaline, and altered sodium concentration on AVN cell activity.
Main Results:
- AVN cells exhibited spontaneous calcium transients and action potentials, often preceded by a slow calcium ramp.
- Ryanodine and isoprenaline modulated the rate of spontaneous activity by altering the calcium ramp slope.
- Changes in extracellular sodium concentration affected spontaneous AVN activity.
Conclusions:
- This study provides the first sub-cellular level insights into calcium handling within the AVN.
- Cellular calcium cycling is directly implicated in the generation of spontaneous electrical activity in the AVN.
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