Isolation, identification and synthesis of an endogenous arachidonic amide that inhibits calcium channel antagonist 1,4-dihydropyridine binding

Prostaglandins Leukot Essent Fatty Acids. 1993 Jun;48(6):429-37. doi: 10.1016/0952-3278(93)90048-2.


This study was part of a broad search for endogenous regulators of L-type calcium channels. The screening for active fractions was done by measuring inhibition [3H]1,4-dihydropyridine (DHP) binding to rat cardiac and cortex membranes. An inhibitory fraction, termed lyophilized brain hexane-extractable inhibitor (LBHI), was isolated from hexane extracts of lyophilized calf brain. The active substance was purified by a series of chromatographic steps. 13C nuclear magnetic resonance (NMR), 1H coherence spectroscopy (COSY) NMR and fast atom bombardment (FAB) mass spectroscopy suggested that LBHI was N-arachidonic acid-2-hydroxyethylamide. Synthesis of this substance and subsequent high performance liquid chromatography (HPLC) and NMR analysis confirmed this structure. Synthetic LBHI (SLBHI) inhibited [3H]DHP binding to rat cortex membranes with an IC50 value of congruent to 15 microM and a Hill coefficient of congruent to 2. Saturation analysis in the presence of SLBHI showed a change in KD (equilibrium dissociation constant), but not maximal binding capacity (Bmax). SLBHI produced an increased dissociation rate, which, along with the Hill slope of > 1, suggested a non-competitive interaction with the DHP binding site. The results suggest that arachidonic acid derivatives may be endogenous modifiers of the DHP calcium antagonist binding site.

MeSH terms

  • Animals
  • Arachidonic Acids / chemical synthesis
  • Arachidonic Acids / isolation & purification*
  • Arachidonic Acids / pharmacology*
  • Calcium Channel Blockers / antagonists & inhibitors*
  • Cattle
  • Cerebral Cortex / metabolism
  • Chemical Fractionation
  • Chromatography, High Pressure Liquid
  • Dihydropyridines / antagonists & inhibitors*
  • Dihydropyridines / metabolism
  • Dose-Response Relationship, Drug
  • Endocannabinoids
  • Heart Ventricles / metabolism
  • Magnetic Resonance Spectroscopy
  • Mass Spectrometry
  • Polyunsaturated Alkamides
  • Rats


  • Arachidonic Acids
  • Calcium Channel Blockers
  • Dihydropyridines
  • Endocannabinoids
  • Polyunsaturated Alkamides
  • 1,4-dihydropyridine
  • anandamide