title: Short-term effects of palmitate and 2-bromopalmitate on the lipolytic activity of rat adipocytes.
abstract: OBJECTIVE
  Fatty acids are involved in the regulation of lipolysis in adipocytes; however, this regulatory action is unclear. The present study aimed to determine the short-term influence of palmitate and its non-metabolisable analogue, 2-bromopalmitate, on the lipolytic activity of adipocytes.
  
  
  METHODS
  Freshly isolated rat adipocytes were exposed to lipolytic modulators with or without palmitate or 2-bromopalmitate. Glycerol released from cells was determined as an indicator of lipolysis. Moreover, cAMP, ATP and changes in mitochondrial membrane potential were measured in cells treated with 2-bromopalmitate.
  
  
  RESULTS
  It was demonstrated that glycerol release from adipocytes incubated with epinephrine alone or epinephrine with insulin was unchanged by palmitate. However, 2-bromopalmitate was found to significantly decrease lipolysis stimulated by epinephrine or dibutyryl-cAMP. The inhibitory effect of 2-bromopalmitate on lipolysis was accompanied by reduced cAMP in adipocytes. Moreover, 2-bromopalmitate diminished hyperpolarisation of the inner mitochondrial membrane. Adipocyte exposure to 2-bromopalmitate also resulted in a substantial ATP depletion. The effects of 2-bromopalmitate on lipolysis and on ATP content were prevented neither by high glucose nor by alanine in the incubation medium.
  
  
  CONCLUSIONS
  These findings demonstrate that short-term adipocyte exposure to palmitate disturbs neither the lipolytic action of epinephrine nor the antilipolytic action of insulin. However, 2-bromopalmitate significantly decreases lipolysis probably due to impaired metabolic activity of mitochondria.
authors.affiliation: Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland. tszkudel@jay.up.poznan.pl
authors.forename: Tomasz
authors.initials: T
authors.lastname: Szkudelski
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Szkudelska
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D008066:Lipolysis; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism; D010168:Palmitates / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010168:Palmitates; C022776:2-bromopalmitate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D005990:Glycerol