title: Two-photon imaging of endothelin-1-mediated intracellular Ca(2+) handling in smooth muscle cells of rat renal resistance arteries.
abstract: OBJECTIVE
  Endothelin-1 (ET-1) is a potent vasoconstrictor which regulates the physiology of cardiorenal system. The aim of this study was to evaluate ET-1-mediated elevation of intracellular Ca(2+) in smooth muscle cells (SMC) of renal resistance arteries.
  
  
  METHODS
  In in vitro studies of primary SMC, which were isolated from rat renal microvessels, the levels of intracellular Ca(2+) were calculated from the ratio of emissions at 340 and 380nm after loading cells with Fura 2-AM dye. In ex vivo studies we used two-photon imaging of renal resistance arteries excised from rat kidneys and loaded with fluorescent Ca(2+) indicator Fluo-4 AM.
  
  
  RESULTS
  The two-photon imaging demonstrates that treatment of isolated rat renal resistance arteries with ET-1 causes a rapid increase of intracellular Ca(2+) concentration in smooth muscle vasculature of these vessels. These ex vivo observations are in accordance with in vitro findings indicating that ET-1 mediates activation of TRPC channels and increases the level of intracellular Ca(2+) in cultured SMC to 510±83nM.
  
  
  CONCLUSIONS
  ET-1-mediated elevation of intracellular Ca(2+) is strongly linked to renal microvascular contraction and is crucial for ET-1-induced contraction of SMC. The two-photon imaging of intracellular Ca(2+) in intact SMC of rat renal resistance arteries is a powerful technique which allows the detailed ex vivo analysis of intracellular Ca(2+) handling by ET-1, an important player in hypertension-related kidney diseases.
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Oleg
authors.initials: O
authors.lastname: Palygin
authors.affiliation: Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Miller
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Daria V
authors.initials: DV
authors.lastname: Ilatovskaya
authors.affiliation: Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA. Electronic address: Sorokin@mcw.edu.
authors.forename: Andrey
authors.initials: A
authors.lastname: Sorokin
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Staruschenko
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D019332:Endothelin-1 / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D017785:Photons; D051381:Rats; D012077:Renal Artery / Q000187:drug effects* / Q000378:metabolism
chemical_list: D019332:Endothelin-1; D002118:Calcium
keywords: Contraction; Fluo-4 AM; Microvasculature; Renal resistance arteries