Asian Science Citation Index is committed to provide an authoritative, trusted and significant information by the coverage of the most important and influential journals to meet the needs of the global scientific community.  
ASCI Database
308-Lasani Town,
Sargodha Road,
Faisalabad, Pakistan
Fax: +92-41-8815544
Contact Via Web
Suggest a Journal
 
Articles by M. G Chang
Total Records ( 1 ) for M. G Chang
  M. G Chang , Y Zhang , C. Y Chang , L Xu , R Emokpae , L Tung , E Marban and M. R. Abraham
 

Rationale: Reentry underlies most ventricular tachycardias (VTs) seen postmyocardial infarction (MI). Mapping studies reveal that the majority of VTs late post-MI arise from the infarct border zone (IBZ).

Objective: To investigate reentry dynamics and the role of individual ion channels on reentry in in vitro models of the "healed" IBZ.

Methods and Results: We designed in vitro models of the healed IBZ by coculturing skeletal myotubes with neonatal rat ventricular myocytes and performed optical mapping at high temporal and spatial resolution.

In culture, neonatal rat ventricular myocytes mature to form striated myocytes and electrically uncoupled skeletal myotubes simulate fibrosis seen in the healed IBZ. High resolution mapping revealed that skeletal myotubes produced localized slowing of conduction velocity (CV), increased dispersion of CV and directional-dependence of activation delay without affecting myocyte excitability. Reentry was easily induced by rapid pacing in cocultures; treatment with lidocaine, a Na+ channel blocker, significantly decreased reentry rate and CV, increased reentry path length and terminated 30% of reentrant arrhythmias (n=18). In contrast, nitrendipine, an L-type Ca2+ channel blocker terminated 100% of reentry episodes while increasing reentry cycle length and path length and decreasing reentry CV (n=16). K+ channel blockers increased reentry action potential duration but infrequently terminated reentry (n=12).

Conclusions: Cocultures reproduce several architectural and electrophysiological features of the healed IBZ. Reentry termination by L-type Ca2+ channel, but not Na+ channel, blockers suggests a greater Ca2+-dependence of propagation. These results may help explain the low efficacy of pure Na+ channel blockers in preventing and terminating clinical VTs late after MI.

 
 
 
Copyright   |   Desclaimer   |    Privacy Policy   |   Browsers   |   Accessibility