Cardiac norepinephrine transporter protein expression is inversely correlated to chamber norepinephrine content.
The cardiac neuronal norepinephrine (NE) transporter (NET) in sympathetic neurons is responsible for uptake of released NE from the neuroeffector junction. The purpose of this study was to assess the chamber distribution of cardiac NET protein measured using [(3)H]nisoxetine binding in rat heart membranes and to correlate NE content to NET amount. In whole mounts of atria, NET was colocalized in nerve fibers with tyrosine hydroxylase (TH) immunoreactivity. NE content expressed as micrograms NE per gram tissue was lowest in the ventricles; however, NET binding was significantly higher in the left ventricle than the right ventricle and atria (P < 0.05), resulting in a significant negative correlation (r(2) = 0.922; P < 0.05) of NET to NE content. The neurotoxin 6-hydroxydopamine, an NET substrate, reduced NE content more in the ventricles than the atria, demonstrating functional significance of high ventricular NET binding. In summary, there is a ventricular predominance of NET binding that corresponds to a high NE reuptake capacity in the ventricles, yet negatively correlates to tissue NE content.
Dept. of Physiology, Michigan State Univ., East Lansing, MI 48823, USA.
Erica A
EA
Wehrwein
Lindsay M
LM
Parker
Anna A
AA
Wright
John M
JM
Spitsbergen
Martin
M
Novotny
Dagmar
D
Babankova
Greg M
GM
Swain
Beth A
BA
Habecker
David L
DL
Kreulen
D000818:Animals; D015153:Blotting, Western; D005473:Fluoxetine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D006321:Heart / Q000294:innervation* / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000378:metabolism*; D016627:Oxidopamine; D051381:Rats; D017207:Rats, Sprague-Dawley; D013233:Stellate Ganglion / Q000378:metabolism*; D013563:Sympathectomy, Chemical; D013565:Sympatholytics; D014316:Tritium
D050484:Norepinephrine Plasma Membrane Transport Proteins; C493226:Slc6a2 protein, rat; D013565:Sympatholytics; D005473:Fluoxetine; D014316:Tritium; C011386:nisoxetine; D016627:Oxidopamine; D009638:Norepinephrine