title: Immunolocalization of the calcium-sensing receptor in developing human kidney.
abstract: BACKGROUND
  The calcium-sensing receptor (CSR) is a G-protein receptor that plays a critical role in calcium regulation. In the kidney, the CSR regulates calcium reabsorption in the thick ascending limb, where stimulation of the CSR inhibits calcium reabsorption in response to increased calcium in the peritubular fluid. In the collecting duct, apical CSR activation may play a role in osmoregulation, increasing water excretion in response to increased luminal calcium.
  
  
  METHODS
  We studied the ontogeny of the CSR in developing human kidney using immunohistochemical methods.
  
  
  RESULTS
  The CSR is first expressed in the S-shaped body in the region destined to form the ascending limb and distal tubule. Other regions of the S-shaped body, as well as ureteric buds, do not express the CSR. The CSR is observed in thick ascending limb as early as 20 wk of development. The CSR is not observed in proximal tubule or collecting duct between 20 and 40 wk of human development.
  
  
  CONCLUSIONS
  During early human renal development, CSR expression is limited to the thick ascending limb and distal tubule, where this receptor may play a role in calcium homeostasis between 20 and 40 wk of human development.
authors: Department of Pathology, Baystate Medical Center, Tufts University School of Medicine, Springfield, Massachusetts, USA.
authors: Giovanna M
authors: GM
authors: Crisi
authors: Gary F
authors: GF
authors: Rockwell
authors: Gregory L
authors: GL
authors: Braden
authors: Thomas J
authors: TJ
authors: Campfield
mesh_terms: D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000196:embryology* / Q000378:metabolism; D044169:Receptors, Calcium-Sensing / Q000378:metabolism*
chemical_list: D044169:Receptors, Calcium-Sensing