Expression of diverse Na+ channel messenger RNAs in rat myocardium. Evidence for a cardiac-specific Na+ channel.
This study examined the diversity of Na+ channel gene expression in intact cardiac tissue and purified myocardial cells. The screening of neonatal rat myocardial cell cDNA libraries with a conserved rat brain Na+ channel cDNA probe, resulted in the isolation and characterization of a putative rat cardiac Na+ channel cDNA probe (pCSC-1). The deduced amino acid sequence of pCSC-1 displayed a striking degree of homology with the eel, rat brain-1, and rat brain-2 Na+ channel, thereby identifying pCSC-1 as a related member of the family of Na+ channel genes. Northern blot analysis revealed the expression of a 7-kb CSC-1 transcript in rat cardiac tissue and purified myocardial cells, but little or no detectable expression of CSC-1 in rat brain, skeletal muscle, denervated skeletal muscle, or liver. Using RNase protection and Northern blot hybridization with specific rat brain Na+ channel gene probes, expression of the rat brain-1 Na+ channel was observed in rat myocardium, but no detectable expression of the rat brain-2 gene was found. This study provides evidence for the expression of diverse Na+ channel mRNAs in rat myocardium and presents the initial characterization of a new, related member of the family of Na+ channel genes, which appears to be expressed in a cardiac-specific manner.
Sills
M N
MN
Department of Medicine, University of California, San Diego, La Jolla 92093.
Xu
Y C
YC
Baracchini
E
E
Goodman
R H
RH
Cooperman
S S
SS
Mandel
G
G
Chien
K R
KR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000201:enzymology; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010770:Phosphotransferases / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D015222:Sodium Channels / Q000378:metabolism*
D012333:RNA, Messenger; D015222:Sodium Channels; D010770:Phosphotransferases