title: A new electrochemical HPLC method for analysis of enkephalins and endomorphins.
abstract: Endogenous opioid peptides, enkephalins and endomorphins, are located in key regions involved in pain transmission and analgesia, including the spinal cord. These endogenous peptides activate opioid receptors to produce analgesia and reduce pain. We describe a new method to measure enkephalin and endomorphins by high performance liquid chromatography with electrochemical detection. This method allows use of a small sample volume to measure met-enkephalin, leu-enkephalin, endomorphin-1 and endomorphin-2 simultaneously. Using push-pull perfusion of the spinal cord, there were detectable concentrations of met-enkephalin, leu-enkephalin, and endomorphin-2. Further infusion of 100mM potassium chloride evoked release of met-enkephalin and endomorphin-2 but not leu-enkephalin. Thus, we have developed a method to simultaneously measure enkephalins and endomorphins in small sample volume that allows measurement of these opioid peptides in vivo.
authors.affiliation: Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-242 Medical Education Building, Iowa City, IA 52242-1190, USA.
authors.forename: Tammy L
authors.initials: TL
authors.lastname: Lisi
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Sluka
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004743:Enkephalin, Leucine / Q000032:analysis* / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000032:analysis* / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D009842:Oligopeptides / Q000032:analysis* / Q000378:metabolism; D010146:Pain / Q000378:metabolism; D010477:Perfusion; D020671:Posterior Horn Cells / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical
chemical_list: D009842:Oligopeptides; C105293:endomorphin 1; C105294:endomorphin 2; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D011189:Potassium Chloride