Cardiac calcium dysregulation in mice with chronic kidney disease

Area of Science:

• Cardiology
• Nephrology
• Molecular Biology

Background:

• Cardiovascular complications are a major cause of death in chronic kidney disease (CKD) patients.
• The precise mechanisms by which CKD disrupts cardiac calcium (Ca²⁺) regulation remain unclear.

Purpose of the Study:

• To investigate the alterations in cardiac Ca²⁺ homeostasis in a mouse model of CKD.
• To explore the role of Ca²⁺ handling proteins and electrophysiological changes in CKD-associated cardiac dysfunction.

Main Methods:

• Echocardiography and electrocardiography were used to assess cardiac function and electrophysiology in CKD mice.
• Intracellular Ca²⁺ measurements (microelectrodes, Fluo-3) were performed on ventricular cardiomyocytes.
• Western blot analysis was employed to evaluate protein expression and phosphorylation levels (RyR2, CaMKII, SERCA2, PLB).

Main Results:

• CKD mice showed impaired cardiac function (reduced fractional shortening, stroke volume) and prolonged QT interval.
• Ventricular cardiomyocytes from CKD mice exhibited altered Ca²⁺ handling, including increased Ca²⁺ decay time, sparks, and leakage, but reduced Ca²⁺ transients and sarcoplasmic reticulum Ca²⁺ content.
• Inhibition of CaMKII (with KN93) and late sodium current (with ranolazine) improved Ca²⁺ handling and reversed electrophysiological abnormalities.

Conclusions:

• CKD significantly alters cardiac Ca²⁺ regulation through modulation of CaMKII, phospholamban (PLB), and the late sodium current.
• These molecular and cellular changes contribute to the observed electrophysiological abnormalities and impaired cardiac function in CKD.
• Targeting these pathways presents a potential therapeutic strategy for managing cardiovascular complications in CKD.