High Glucose Concentration Does Not Modulate the Formation of Arterial Medial Calcification in Experimental Uremic Rats

Abstract

High phosphate-induced phenotypic switching of smooth muscle cells (SMCs) into osteogenic cells is critical for the formation of arterial medial calcification in chronic kidney disease. Because vascular calcification is also prevalent in type 2 diabetes, we examined whether glucose concentration affects high phosphate-induced SMC phenotypic switching and calcification. First, the formation of arterial medial calcification was compared among 4 groups: adenine-fed uremic rats, streptozotocin-injected hyperglycemic rats, adenine-fed and streptozotocin-injected uremic/hyperglycemic rats, and control rats. Calcification was obvious in uremic and uremic/hyperglycemic rats, whereas it was undetectable in the others. Aortic calcium contents were significantly elevated in uremic and uremic/hyperglycemic rats, but they were not different between the two groups. Moreover, hyperglycemia had no effects on the reduced expression of SMC differentiation markers including smooth muscle α-actin and SM22α and on the increased expression of osteogenic markers, such as Runx2, in uremic rats. Second, cultured SMCs were incubated in the medium with various concentrations of phosphate (0.9-4.5 mmol/l) and glucose (5-50 mmol/l), and calcium deposition was measured. Although high phosphate dose-dependently increased calcium contents, they were unaffected by glucose concentration. Results suggest that glucose concentration does not directly modulate high phosphate-induced SMC phenotypic switching and arterial medial calcification.

Smooth Muscle–Selective Nuclear Factor‐κB Inhibition Reduces Phosphate‐Induced Arterial Medial Calcification in Mice With Chronic Kidney Disease

“…We sought to establish another CKD mouse model with arterial medial calcification. An adenine‐induced CKD rat model is widely used to study arterial medial calcification . Thus, we first fed a diet containing 0.75% adenine, the same concentration of adenine as that used in the rat model, to DBA/2 mice to induce CKD.…”

“…Most studies reported in the field of arterial medial calcification thus far have been performed using an adenine‐fed rat model . Unfortunately, this model has limitations in regard to gain‐of‐function experiments and loss‐of‐function experiments because of the use of rats, rather than mice.…”

“…The arteries and the hearts for histology and immunostaining were fixed in 4% paraformaldehyde and embedded into OCT compound. The 6‐μm cross‐sections were prepared and subjected to von Kossa staining, Alizarin red staining, Masson trichrome staining, and immunostaining, as described previously . A morphometric analysis of the thoracic aorta was performed using 3 Alizarin red‐stained sections per artery.…”

Dipeptidyl peptidase-4 inhibitor gemigliptin protects against vascular calcification in an experimental chronic kidney disease and vascular smooth muscle cells

“…Suggested underlying mechanisms of phosphate-induced VC are as follows: osteoblastic phenotype change of VSMCs, VSMC apoptosis, loss of inhibitors, extracellular matrix degradation, and release of matrix vesicles [30–32]. The type III sodium-dependent phosphate transporter PiT-1 is more predominantly expressed in human VSMCs [24, 25].…”

Deletion of Krüppel‐Like Factor 4 in Endothelial and Hematopoietic Cells Enhances Neointimal Formation Following Vascular Injury

“…Staining for Klf4, Ki67, CD3ε, Mac2, Vcam1, and E‐selectin was visualized by diaminobenzidine, and sections were counterstained by hematoxylin . Staining for SM α‐actin and SM22α was visualized by a Vector Red Alkaline Phosphatase Substrate kit (Vector Laboratories, Burlingame, CA), and sections were counterstained by hematoxylin …”