Reduced DHPRα1S and RyR1 expression levels are associated with diaphragm contractile dysfunction during sepsis

Area of Science:

• Physiology
• Molecular Biology
• Pathology

Background:

• Sepsis commonly leads to diaphragm dysfunction.
• Dihydropyridine receptors (DHPRα1s, DHPRα1c) and ryanodine receptors (RyR1, RyR2, RyR3) are critical for muscle excitation-contraction coupling.
• Receptor expression in the diaphragm during sepsis remains unexplored.

Purpose of the Study:

• To investigate the expression of DHPRs and RyRs in the diaphragm during sepsis.
• To determine the relationship between receptor expression and diaphragm contractile function in sepsis.

Main Methods:

• Sepsis was induced in rats using endotoxin.
• Diaphragm isometric contractile force was measured.
• mRNA and protein levels of DHPRs and RyRs in diaphragm muscles were quantified.

Main Results:

• Sepsis significantly reduced diaphragm contractile function.
• Expression of DHPRα1s and RyR1 (skeletal muscle isoforms) was significantly lower in septic rats.
• DHPRα1c and RyR3 expression remained unchanged; RyR2 was undetectable.

Conclusions:

• Reduced diaphragm contraction in sepsis is linked to decreased expression of DHPRα1s and RyR1.
• These findings highlight specific molecular changes contributing to sepsis-induced diaphragm dysfunction.