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[Changes in the localization of the cardiac pacemaker in the rabbit sinus node during hyperkalemia]
Kardiologiia
|November 1, 1983
Summary
Elevated extracellular potassium ions ([K+]o) caused the rabbit cardiac pacemaker to shift within the sinus node. This migration altered atrial contractions and electrical activation, revealing significant sinus node functional heterogeneity.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Physiology
Context:
- The cardiac pacemaker's location is crucial for normal heart rhythm.
- Extracellular ion concentrations, particularly potassium, significantly influence cardiac function.
- The sinus node's precise electrophysiological properties are not fully understood.
Purpose:
- To investigate the effect of elevated extracellular potassium concentrations ([K+]o) on the localization of the cardiac pacemaker in isolated rabbit right atrium preparations.
- To determine if shifts in pacemaker localization correlate with changes in atrial electrophysiology and contractility.
Summary:
- Elevated [K+]o (10.8 mM) induced a significant shift of the cardiac pacemaker from the superior to the inferior sinus node in rabbit right atria.
- Pacemaker migration occurred through 2-4 intermediate positions along the terminal crest, accompanied by altered spontaneous contractions and right atrial electrical activation patterns.
- Reperfusion with normal [K+]o reversed the pacemaker migration, with 3-5 intermediate positions observed, highlighting functional heterogeneity within the sinus node.
Impact:
- Demonstrates marked functional heterogeneity within the sinus node.
- Provides insights into the electrophysiological mechanisms underlying pacemaker localization and atrial activation.
- Suggests that ion channel activity and ion gradients play a critical role in regulating pacemaker behavior.