Connexin 43 impacts on mitochondrial potassium uptake

Area of Science:

• Cardiology
• Mitochondrial Biology
• Cellular Physiology

Background:

• Connexin 43 (Cx43) is found in cardiomyocyte mitochondria, not just plasma membranes.
• Cx43's role in mitochondrial function, particularly potassium transport, is not fully understood.
• Mitochondrial Cx43 impacts ADP-stimulated respiration, suggesting a role in energy metabolism.

Purpose of the Study:

• To investigate the effect of connexin 43 (Cx43) on mitochondrial potassium uptake.
• To determine if pharmacological inhibition or genetic ablation of Cx43 alters mitochondrial potassium influx.
• To link Cx43-mediated potassium transport to mitochondrial respiration.

Main Methods:

• Isolated subsarcolemmal mitochondria (SSM) from rat myocardium.
• Utilized the potassium-sensitive dye PBFI to measure intramitochondrial potassium.
• Administered Gap19 (Cx43 inhibitor) and used Cx43 conditional knockout mice (4-OHT induced).

Main Results:

• Pharmacological inhibition of Cx43 with Gap19 reduced mitochondrial potassium influx by approximately 35%.
• Genetic ablation of Cx43 in knockout mice also decreased mitochondrial potassium influx by approximately 33%.
• Both methods demonstrated a significant reduction in potassium uptake velocity in the absence of functional Cx43.

Conclusions:

• Mitochondrial connexin 43 (Cx43) plays a crucial role in regulating mitochondrial potassium influx.
• Inhibition or genetic removal of Cx43 significantly impairs mitochondrial potassium uptake.
• These findings suggest Cx43 is a key modulator of mitochondrial ion transport and potentially cellular respiration.