title: Assessing physiological concentrations of endogenous substances in situ by inducing calcium oscillations in vitro. Case of liver.
abstract: OBJECTIVE
  To identify the physiological concentration ranges of norepinephrine (NE), vasopressin (VP), and ATP in the rat liver.
  
  
  METHODS
  Rat hepatocytes were isolated by collagenase perfusion. Isolated cells were loaded with the fluorescent calcium indicator Fura-2 acetoxymethyl ester (Fura-2 AM). The effects of different concentrations of norepinephrine, vasopressin, and ATP on intracellular calcium concentration ([Ca2+]i) increases in the freshly isolated rat hepatocytes were investigated. [Ca2+]i was measured by microfluorometry and recorded as fluorescence ratios (F340/F380).
  
  
  RESULTS
  NE, VP, and ATP induced increases in [Ca2+]i in a concentration-dependent manner. At lower concentrations, [Ca2+]i tended to show an oscillatory increase; with increasing concentrations, [Ca2+]i in more cells tended to show phasic or plateau increases. NE, VP, and ATP concentrations likely to induce an oscillatory [Ca2+]i response were 100 - 500 nmol/L, 50 - 100 pmol/L, and < 1 micromol/L respectively.
  
  
  CONCLUSIONS
  Physiological concentrations of NE, VP, and ATP are 100 - 500 nmol/L, 50 - 100 pmol/L, and < 1 micromol/L respectively in the rat liver.
authors.affiliation: Institute of Cell Biology, Beijing Normal University, Beijing 100875, China. zjcui@bnu.edu.cn
authors.forename: Zong-Jie
authors.initials: ZJ
authors.lastname: Cui
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Guo
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D016257:Fura-2; D022781:Hepatocytes / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000032:analysis / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014667:Vasopressins / Q000032:analysis / Q000502:physiology*
chemical_list: D014667:Vasopressins; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2; D009638:Norepinephrine