title: Ventricular muscarinic receptor remodeling in patients with and without primary ventricular fibrillation. An imaging study.
abstract: BACKGROUND
  Vagal innervation modulates the electrical stability of the left ventricle (LV) during ischemia. Thus, abnormal parasympathetic activity in myocardial infarction (MI) patients with primary ventricular fibrillation (FV) can account for their arrhythmic disorders. We evaluated LV muscarinic receptor density (B (max)) after MI in patients with (FV(G), n = 11) or without (nFV(G), n = 12) primary FV.
  
  
  RESULTS
  The B (max) was measured by positron emission tomography and the specific antagonist [(11)C]methylquinuclidinyl benzilate ([(11)C]MQNB) in 23 patients 39 ± 19 days post-MI, and 10 volunteers. Myocardial damage was quantified by delayed contrast-enhanced magnetic resonance imaging. Three short-axis slices per subject were analyzed and six time-activity curves per slice were fitted to a 3-compartment ligand-receptor model. The B (max) in remote regions of the 23 patients (67 ± 36 pmol/mL · tissue; n = 139) was higher than in normal regions of volunteers (33 ± 16 pmol/mL · tissue; n = 171; P = .01). Receptor density in remote regions was similarly upregulated in nFV(G) (69 ± 31 pmol/mL · tissue, n = 73) and FV(G) (66 ± 40 pmol/mL · tissue, n = 66; P = .72). In damaged regions, the B (max) was reduced in both patient groups (44 pmol/mL · tissue).
  
  
  CONCLUSIONS
  Chronically infarcted patients with or without primary FV share similar patterns of ventricular muscarinic receptor remodeling, characterized by receptor upregulation, in remote non-damaged territories.
authors.affiliation: CERMEP-Imagerie du Vivant, Lyon, France.
authors.forename: Alejandro N
authors.initials: AN
authors.lastname: Mazzadi
authors.forename: Julien
authors.initials: J
authors.lastname: Pineau
authors.forename: Nicolas
authors.initials: N
authors.lastname: Costes
authors.forename: Didier
authors.initials: D
authors.lastname: Le Bars
authors.forename: Fréderic
authors.initials: F
authors.lastname: Bonnefoi
authors.forename: Raphaël
authors.initials: R
authors.lastname: Porcher
authors.forename: Pierre
authors.initials: P
authors.lastname: Croisille
authors.forename: Philippe
authors.initials: P
authors.lastname: Chevalier
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000378:metabolism; D049268:Positron-Emission Tomography; D011976:Receptors, Muscarinic / Q000032:analysis*; D014693:Ventricular Fibrillation / Q000378:metabolism*; D020257:Ventricular Remodeling
chemical_list: D011976:Receptors, Muscarinic