Ryanodine receptor-mediated Ca2+ events in atrial myocytes of patients with atrial fibrillation

Area of Science:

• Cardiology
• Molecular Biology
• Cell Physiology

Background:

• Atrial fibrillation (AF) is linked to altered sarcoplasmic reticulum Ca(2+) handling proteins in atrial myocytes.
• The functional impact of these protein alterations on Ca(2+) handling in AF remains largely unknown.

Purpose of the Study:

• To investigate if ryanodine receptor (RyR)-mediated intracellular Ca(2+) events are affected by protein alterations in AF atrial myocytes.
• To analyze spontaneous Ca(2+) sparks and Ca(2+) waves in atrial myocytes from AF and normal sinus rhythm (NSR) patients.

Main Methods:

• Laser scanning confocal microscopy was used to examine intact and permeabilized atrial myocytes.
• Compared Ca(2+) spark and wave properties between AF patients (n=21) and NSR patients (n=22).

Main Results:

• Ca(2+) spark frequency, amplitude, and rise time were similar between AF and NSR groups.
• AF atrial myocytes showed significantly increased full width and full duration at half maximum intensity for Ca(2+) sparks.
• The frequency of both small and global Ca(2+) waves increased in AF atrial myocytes.

Conclusions:

• Spatiotemporal properties, not frequency, of Ca(2+) sparks are affected in AF atrial myocytes.
• Increased frequency of Ca(2+) waves was observed in AF atrial myocytes.
• The observed alterations in RyR-mediated Ca(2+) events differ from previous studies, warranting further investigation into underlying mechanisms.