Vascular Calcification Is Accelerated by Hyponatremia and Low Osmolality

Area of Science:

• Nephrology
• Cardiovascular Biology
• Cell Biology

Background:

• Hyponatremia is prevalent in chronic kidney disease (CKD) and linked to cardiovascular risks.
• Low osmolality is known to induce oxidative stress and cell death, potentially accelerating vascular calcification (VC).
• The specific role of hyponatremia or low osmolality in the pathogenesis of VC remains unclear.

Purpose of the Study:

• To investigate the role of hyponatremia and low osmolality in the development of vascular calcification.
• To elucidate the underlying cellular mechanisms and signaling pathways involved in osmolality-related VC.

Main Methods:

• Cultured human vascular smooth muscle cells (VSMCs) and mouse aortic rings under varying osmotic conditions and calcifying media.
• Examined VSMC phenotypic changes, oxidative stress, and gene expression via microarray analysis.
• Utilized live imaging to visualize ion flux and analyzed human autopsy specimens for associations between arterial calcification and hyponatremia.

Main Results:

• Low osmolality significantly exacerbated extracellular matrix calcification in VSMCs and aortic rings.
• Identified oxidative stress and VSMC osteogenic differentiation as key mechanisms.
• Discovered that low osmolality activates the Rac1-Akt pathway and reduces NCX1 expression, impacting calcium and sodium ion flux.
• Observed accelerated calciprotein particle (CPP) formation and maturation.
• Found a positive association between hyponatremia/low osmolality and arterial intimal calcification in human autopsy data.

Conclusions:

• Hyponatremia and low osmolality promote vascular calcification through multiple cellular processes.
• Activation of the Rac1-Akt pathway is a key mechanism in osmolality-induced VC.