title: Loss of bladder smooth muscle caveolae in the aging bladder.
abstract: OBJECTIVE
  Caveolae are specialized regions of the cell membrane that modulate signal transduction and alterations in these structures affect bladder smooth muscle (BSM) contraction. Since bladder dysfunctions are common in the elderly, we evaluated the effect of aging on the morphology of caveolae and caveolin protein expression in BSM.
  
  
  METHODS
  Caveolar morphology (number, size, and depth) in BSM was determined from electron microscopy images of young (10 weeks), adult (6-month old), and old (12-month old) rat urinary bladders. Changes in expression levels of caveolin proteins with age were investigated by Western blot and immunofluorescence microscopy. Caveolin-3 gene expression was determined by real-time RT-PCR in young and 19-month-old rat bladders.
  
  
  RESULTS
  Twelve-month-old animals exhibited 50% fewer BSM caveolae compared to young (P < 0.01). The area of caveolae was significantly decreased at 6 and 12 months. Despite a decrease in the number of BSM caveolae at 12 months, the expression of caveolin-1 and cavin-1 were unaltered with age. In contrast, caveolin-2 and caveolin-3 protein expression and immunoreactivity were reduced in BSM at 6 and 12 months of age. Caveolin-3 gene expression was also downregulated at 19 months compared to young animals.
  
  
  CONCLUSIONS
  Biological aging significantly decreases BSM caveolae number and morphology with associated selective alteration in caveolin protein expression. Since caveolae are protected membrane regions that regulate signal transduction, age-related alterations in caveolae and caveolin protein expression could alter BSM contractility resulting in bladder dysfunctions of the elderly.
authors.affiliation: Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Samar K
authors.initials: SK
authors.lastname: Lowalekar
authors.forename: Vivian
authors.initials: V
authors.lastname: Cristofaro
authors.forename: Ziv M
authors.initials: ZM
authors.lastname: Radisavljevic
authors.forename: Subbarao V
authors.initials: SV
authors.lastname: Yalla
authors.forename: Maryrose P
authors.initials: MP
authors.lastname: Sullivan
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D021941:Caveolae / Q000378:metabolism / Q000473:pathology*; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism; D051243:Caveolin 2 / Q000235:genetics / Q000378:metabolism; D051244:Caveolin 3 / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000378:metabolism / Q000473:pathology*
chemical_list: D051242:Caveolin 1; D051243:Caveolin 2; D051244:Caveolin 3