Dopamine synthesis and release in LLC-PK1 cells.

A porcine-derived renal epithelial cell line, LLC-PK1, was used to examine dopamine (DA) synthesis from L-dopa and DA release into the media. DA synthesis and release were elevated by increasing either L-dopa concentration or incubation time. DA synthesis was shown to be entirely due to conversion of L-dopa to DA by aromatic amino acid decarboxylase. DA release from LLC-PK1 cells was stimulated by NaCl and other Na+ or Cl- salts. DA release by LLC-PK1 cells was not dependent on extracellular Ca2+ or significantly stimulated by the depolarizing actions of KCl. LLC-PK1 cells which are devoid of any neural contributions to renal DA production can synthesize DA from L-dopa and release DA in response to stimulation by either Na+ or Cl-.