Heterogeneous sympathetic innervation influences local myocardial repolarization in normally perfused rabbit hearts.
BACKGROUND
Heterogeneity of sympathetic innervation is thought to contribute to the potential for fatal arrhythmia. However, little is known about the effects of heterogeneous innervation on repolarization.


RESULTS
To assess this relationship, we measured activation recovery intervals (ARIs) from 64 epicardial sites in 11 rabbits studied 2 weeks after regional denervation produced by phenol and 4 sham-operated rabbits. ARI results were compared with the distribution of sympathetic innervation measured from 3D reconstructions of serial autoradiographs of [(125)I]metaiodobenzylguanidine and (99m)Tc-sestamibi. ARIs were recorded during baseline sinus rhythm, norepinephrine (NE) infusion (0.1 microg. kg(-1). min(-1)), and left stellate ganglion stimulation (SS). NE shortened ARI in 98% of electrodes in the denervated region. The degree of ARI shortening and dispersion increased (P<0.001 and P<0.01, respectively) as denervation became more severe. SS shortened ARI in 30% of electrodes in the denervated area, with increased shortening and dispersion related to increased severity of denervation (P<0.01). SS prolonged ARI in 70% of electrodes in the denervated area, with no correlation with severity of denervation.


CONCLUSIONS
The magnitude and dispersion of local repolarization responses are related to the severity of denervation, as well as the type of stimulation: neural (SS) versus humoral (NE). The differences may relate to the concentration of NE released.
Yoshioka
K
K
Cardiovascular Research Institute, University of California, San Francisco 94143-0252, USA.
Gao
D W
DW
Chin
M
M
Stillson
C
C
Penades
E
E
Lesh
M
M
O'Connell
W
W
Dae
M
M
D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics; D000818:Animals; D001345:Autoradiography; D003714:Denervation; D004558:Electric Stimulation; D004594:Electrophysiology; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D019800:Phenol / Q000494:pharmacology; D011817:Rabbits; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012016:Reference Values; D012597:Sclerosing Solutions / Q000494:pharmacology; D013233:Stellate Ganglion / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics
D019275:Radiopharmaceuticals; D012597:Sclerosing Solutions; D019800:Phenol; D019797:3-Iodobenzylguanidine; D017256:Technetium Tc 99m Sestamibi; D009638:Norepinephrine