Determination of endogenous norepinephrine levels in different chambers of the rat heart by capillary electrophoresis coupled with amperometric detection.
Capillary electrophoresis with end-column amperometric detection (CE-EC) was used to determine the regional distribution of norepinephrine (NE) in the hearts of sympathetically innervated (control) and chemically sympathectomized rats. Key features of the method are (i) the sample preparation and clean-up step that involved the application of off-line solid phase extraction (SPE) with a 95% NE recovery and (ii) the use of a diamond microelectrode for detection. NE was quantified in the left and right ventricle, the ventricular septum, and the left and right atrium. The NE concentration in the atria was three to five times higher than in the ventricles and ventricular septum of control rats. Basal NE levels in the left and right ventricle and the ventricular septum were reduced to below the detection limit (0.034 microg/g tissue) in tissues treated with the neurotoxin, 6-hydroxydopamine (6-OHDA), while only a moderate reduction was observed in the left and right atrium. Importantly, the diamond microelectrode provided low and stable background current and low peak-to-peak noise <or=0.65 pA at a detection potential of +0.86 V versus Ag/AgCl. A reproducible electrode response was observed for multiple injections of tissue homogenates with minimal response attenuation due to electrode fouling.
Novotny
Martin
M
Department of Chemistry and the Neuroscience Program, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322, USA.
Quaiserová-Mocko
Veronika
V
Wehrwein
Erica A
EA
Kreulen
David L
DL
Swain
Greg M
GM
D018663:Adrenergic Agents / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D004563:Electrochemistry / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods*; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D006346:Heart Septum / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D066298:In Vitro Techniques; D017736:Ion-Selective Electrodes; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D016627:Oxidopamine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D018663:Adrenergic Agents; D016627:Oxidopamine; D009638:Norepinephrine