|
|
|
|
|
|
|
||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ARTICLE |
Correspondence to Eric Bennett: esbennet{at}hsc.usf.edu
Voltage-gated sodium channel function from neonatal and adult rat cardiomyocytes was measured and compared. Channels from neonatal ventricles required an 
10 mV greater depolarization for voltage-dependent gating events than did channels from neonatal atria and adult atria and ventricles. We questioned whether such gating shifts were due to developmental and/or chamber-dependent changes in channel-associated functional sialic acids. Thus, all gating characteristics for channels from neonatal atria and adult atria and ventricles shifted significantly to more depolarized potentials after removal of surface sialic acids. Desialylation of channels from neonatal ventricles did not affect channel gating. After removal of the complete surface N-glycosylation structures, gating of channels from neonatal atria and adult atria and ventricles shifted to depolarized potentials nearly identical to those measured for channels from neonatal ventricles. Gating of channels from neonatal ventricles were unaffected by such deglycosylation. Immunoblot gel shift analyses indicated that voltage-gated sodium channel 
subunits from neonatal atria and adult atria and ventricles are more heavily sialylated than subunits from neonatal ventricles. The data are consistent with approximately 15 more sialic acid residues attached to each subunit from neonatal atria and adult atria and ventricles. The data indicate that differential sialylation of myocyte voltage-gated sodium channel subunits is responsible for much of the developmental and chamber-specific remodeling of channel gating observed here. Further, cardiac excitability is likely impacted by these sialic acid–dependent gating effects, such as modulation of the rate of recovery from inactivation. A novel mechanism is described by which cardiac voltage-gated sodium channel gating and subsequently cardiac rhythms are modulated by changes in channel-associated sialic acids.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  D. Isaev, E. Isaeva, T. Shatskih, Q. Zhao, N. C. Smits, N. W. Shworak, R. Khazipov, and G. L. Holmes Role of Extracellular Sialic Acid in Regulation of Neuronal and Network Excitability in the Rat Hippocampus J. Neurosci., October 24, 2007; 27(43): 11587 - 11594. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Johnson and E. S. Bennett Isoform-specific Effects of the beta2 Subunit on Voltage-gated Sodium Channel Gating J. Biol. Chem., September 8, 2006; 281(36): 25875 - 25881. [Abstract] [Full Text] [PDF]
|
|
|
|
