title: Intracellular calcium increases in vascular smooth muscle cells with progression of chronic kidney disease in a rat model.
abstract: Vascular smooth muscle cells (VSMCs) exhibit phenotypic plasticity, promoting vascular calcification and increasing cardiovascular risk. Changes in VSMC intracellular calcium ([Ca 2+ ] i ) are a major determinant of plasticity, but little is known about changes in [Ca 2+ ] i in chronic kidney disease (CKD). We have previously demonstrated such plasticity in aortas from our rat model of CKD and therefore sought to examine changes in [Ca 2+ ] i during CKD progression.
  
  
  
  We examined freshly isolated VSMCs from aortas of normal rats, Cy/+ rats (CKD) with early and advanced CKD, and advanced CKD rats treated without and with 3% calcium gluconate (CKD + Ca 2+ ) to lower parathyroid hormone (PTH) levels. [Ca 2+ ] i was measured with fura-2.
  
  
  
  Cy/+ rats developed progressive CKD, as assessed by plasma levels of blood urea nitrogen, calcium, phosphorus, parathyroid hormone and fibroblast growth factor 23. VSMCs isolated from rats with CKD demonstrated biphasic alterations in resting [Ca 2+ ] i : VSMCs from rats with early CKD exhibited reduced resting [Ca 2+ ] i , while VSMCs from rats with advanced CKD exhibited elevated resting [Ca 2+ ] i . Caffeine-induced sarcoplasmic reticulum (SR) Ca 2+ store release was modestly increased in early CKD and was more drastically increased in advanced CKD. The advanced CKD elevation in SR Ca 2+ store release was associated with a significant increase in the activity of the sarco-endoplasmic reticulum Ca 2+ ATPase (SERCA); however, SERCA2a protein expression was decreased in advanced CKD. Following SR Ca 2+ store release, recovery of [Ca 2+ ] i in the presence of caffeine and extracellular Ca 2+ was attenuated in VSMCs from rats with advanced CKD. This impairment, together with reductions in expression of the Na + /Ca 2+ exchanger, suggest a reduction in Ca 2+ extrusion capability. Finally, store-operated Ca 2+ entry (SOCE) was assessed following SR Ca 2+ store depletion. Ca 2+ entry during recovery from caffeine-induced SR Ca 2+ store release was elevated in advanced CKD, suggesting a role for exacerbated SOCE with progressing CKD.
  
  
  
  With progressive CKD in the Cy/+ rat there is increased resting [Ca 2+ ] i in VSMCs due, in part, to increased SOCE and impaired calcium extrusion from the cell. Such changes may predispose VSMCs to phenotypic changes that are a prerequisite to calcification.
authors: Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Stacey Dineen
authors: SD
authors: Rodenbeck
authors: Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Chad A
authors: CA
authors: Zarse
authors: Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Mikaela L
authors: ML
authors: McKenney-Drake
authors: Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Rebecca S
authors: RS
authors: Bruning
authors: Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Michael
authors: M
authors: Sturek
authors: Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Neal X
authors: NX
authors: Chen
authors: Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.|Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.|Department of Medicine, Roudebush Veterans Affairs Medical Center, Indianapolis, IN, USA.
authors: Sharon M
authors: SM
authors: Moe
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002125:Calcium Gluconate / Q000494:pharmacology; D002318:Cardiovascular Diseases / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D018450:Disease Progression; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D058915:Purinergic P1 Receptor Antagonists / Q000494:pharmacology; D051381:Rats; D051436:Renal Insufficiency, Chronic / Q000378:metabolism*; D012307:Risk Factors; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D061205:Vascular Calcification / Q000378:metabolism*
chemical_list: D058915:Purinergic P1 Receptor Antagonists; D019831:Sodium-Calcium Exchanger; D002110:Caffeine; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002125:Calcium Gluconate; D002118:Calcium
keywords: calcium signaling; cell phenotype; chronic kidney disease; rat model; vascular smooth muscle cells