TY - JOUR
T1 - Glycosylation influences voltage-dependent gating of cardiac and skeletal muscle sodium channels
AU - Zhang, Y.
AU - Hartmann, H. A.
AU - Satin, J.
PY - 1999/10/1
Y1 - 1999/10/1
N2 - The role of glycosylation on voltage-dependent channel gating for the cloned human cardiac sodium channel (hHla) and the adult rat skeletal muscle isoform (μl) was investigated in HEK293 cells transiently transfected with either hHla or μl cDNA. The contribution of sugar residues to channel gating was examined in transfected cells pretreated with various glycosidase and enzyme inhibitors to deglycosylate channel proteins. Pretreating transfected cells with enzyme inhibitors castanospermine and swainsonine, or exo- glycosidase neuroaminidase caused 7 to 9 mV depolarizing shifts of V1/2 for steady-state activation of hHla, while deglycosylation with corresponding drugs elicited about the same amount of depolarizing shifts (8 to 9 mV) of V1/2 for steady-state activation of μl. Elevated concentrations of extracellular Mg2+ significantly masked the castanospermine-elicited depolarizing shifts of V1/2 for steady-state activation in both transfected hHla and μl. For steady-state activation, deglycosylation induced depolarizing shifts of V1/2 for hHla (10.6 to 12 mV), but hyperpolarizing shifts for μl (3.6 to 4.4 mV). Pretreatment with neuraminidase had no significant effects on single-channel conductance, the mean open time, and the open probability. These data suggest that glycosylation differentially regulates Na channel function in heart and skeletal muscle myocytes.
AB - The role of glycosylation on voltage-dependent channel gating for the cloned human cardiac sodium channel (hHla) and the adult rat skeletal muscle isoform (μl) was investigated in HEK293 cells transiently transfected with either hHla or μl cDNA. The contribution of sugar residues to channel gating was examined in transfected cells pretreated with various glycosidase and enzyme inhibitors to deglycosylate channel proteins. Pretreating transfected cells with enzyme inhibitors castanospermine and swainsonine, or exo- glycosidase neuroaminidase caused 7 to 9 mV depolarizing shifts of V1/2 for steady-state activation of hHla, while deglycosylation with corresponding drugs elicited about the same amount of depolarizing shifts (8 to 9 mV) of V1/2 for steady-state activation of μl. Elevated concentrations of extracellular Mg2+ significantly masked the castanospermine-elicited depolarizing shifts of V1/2 for steady-state activation in both transfected hHla and μl. For steady-state activation, deglycosylation induced depolarizing shifts of V1/2 for hHla (10.6 to 12 mV), but hyperpolarizing shifts for μl (3.6 to 4.4 mV). Pretreatment with neuraminidase had no significant effects on single-channel conductance, the mean open time, and the open probability. These data suggest that glycosylation differentially regulates Na channel function in heart and skeletal muscle myocytes.
KW - Activation
KW - Glycosylation
KW - Heart
KW - Inactivation
KW - Ion channels
KW - Patch-clamp
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U2 - 10.1007/s002329900571
DO - 10.1007/s002329900571
M3 - Article
C2 - 10501828
AN - SCOPUS:0033214359
SN - 0022-2631
VL - 171
SP - 195
EP - 207
JO - Journal of Membrane Biology
JF - Journal of Membrane Biology
IS - 3
ER -