Plasmalogen-derived lysolipid induces a depolarizing cation current in rabbit ventricular myocytes

Area of Science:

• Cardiovascular Physiology
• Cellular Electrophysiology
• Biochemistry

Background:

• Plasmalogens are key cardiac phospholipids.
• Cardiac phospholipase A2 (PLA2) activation during ischemia preferentially metabolizes plasmalogens.
• The arrhythmogenic potential of lysoplasmenylcholine (LPLC), a plasmalogen metabolite, is largely unknown.

Purpose of the Study:

• To investigate the electrophysiological effects of LPLC on cardiac myocytes.
• To determine the ionic mechanisms underlying LPLC-induced cellular changes.
• To explore the role of LPLC in ischemia-induced cardiac arrhythmias.

Main Methods:

• Isolated rabbit ventricular myocytes were used.
• Spontaneous contractions were monitored.
• Whole-cell patch-clamp recordings were performed to analyze ionic currents.
• Ionic substitutions and channel blockers (Cd2+, Gd3+, La3+) were employed.

Main Results:

• LPLC induced rapid spontaneous myocyte contractions.
• LPLC caused significant resting membrane potential depolarization via a Na+ influx.
• Lanthanides (Gd3+, La3+) inhibited LPLC-induced currents and contractions, suggesting a role in membrane stabilization.

Conclusions:

• LPLC accumulation, resulting from ischemia-induced plasmalogen breakdown, may contribute to ventricular dysrhythmias.
• LPLC-induced Na+ influx and subsequent depolarization are key mechanisms.
• Further research into plasmalogen metabolism and LPLC's role in cardiac function is warranted.