Human saphenous vein endothelial cells express a tetrodotoxin-resistant, voltage-gated sodium current.
Whole-cell patch-clamp electrophysiological investigation of endothelial cells cultured from human saphenous vein (HSVECs) has identified a voltage-gated Na+ current with a mean peak magnitude of -595 +/- 49 pA (n = 75). This current was inhibited by tetrodotoxin (TTX) in a concentration-dependent manner, with an IC50 value of 4.7 microM, suggesting that it was of the TTX-resistant subtype. An antibody directed against the highly conserved intracellular linker region between domains III and IV of known Na+ channel alpha-subunits was able to retard current inactivation when applied intracellularly. This antibody identified a 245-kDa protein from membrane lysates on Western blotting and positively immunolabeled both cultured HSVECs and intact venous endothelium. HSVECs were also shown by reverse transcription-polymerase chain reaction to contain transcripts of the hH1 sodium channel gene. The expression of Na+ channels by HSVECs was shown using electrophysiology and cell-based enzyme-linked immunosorbent assay to be dependent on the concentration and source of human serum. Together, these results suggest that TTX-resistant Na+ channels of the hH1 isoform are expressed in human saphenous vein endothelium and that the presence of these channels is controlled by a serum factor.
Department of Vascular Surgery, Imperial College School of Medicine at Charing Cross, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, United Kingdom. m.gosling@cxwms.ac.uk
M
M
Gosling
S L
SL
Harley
R J
RJ
Turner
N
N
Carey
J T
JT
Powell
D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001483:Base Sequence; D001769:Blood; D002478:Cells, Cultured; D017931:DNA Primers; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating; D007700:Kinetics; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D012501:Saphenous Vein / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism* / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology*
D017931:DNA Primers; D015222:Sodium Channels; D013779:Tetrodotoxin