Discordant effects of nicotine on endothelial cell proliferation, migration, and the inward rectifier potassium current.
The inward rectifier K+ current (K(ir)) determines the resting membrane potential of endothelial cells. Basic fibroblast growth factor (bFGF) has been shown to activate K(ir) and acts as angiogenic factor and vasodilator. In contrast, nicotine has been demonstrated to reduce endothelium-dependent vasorelaxation by increasing radical formation. Aim of the present study was to investigate whether nicotine modulates K(ir) and if this plays a role in bFGF-mediated proliferation, migration and nitric oxide (NO)-formation of endothelial cells. Using the patch-clamp technique in cultured endothelial cells of human umbilical cord veins (HUVEC), we found characteristic K(ir), which were blocked by extracellular barium (100 micromol/l). Perfusion with nicotine (1 nmol/l-10 micromol/l) revealed a dose-dependent reduction of K(ir). The simultaneous perfusion with bFGF (50 ng/ml) and nicotine (10 micromol/l) still significantly reduced K(ir) (n = 8; P < 0.01). Cell counts revealed that bFGF-mediated proliferation of HUVEC was significantly inhibited when using 1-10 micromol/l nicotine (n = 8, P < 0.01). The bFGF-induced endothelial cell migration--examined using the "Fences-Migration-Assay"--was significantly reduced by 10 mumol/l nicotine (n = 12; P < 0.05). NO-production was examined using a cGMP-Radioimmunoassay. The significant bFGF-induced increase of cGMP-levels was reduced by nicotine (n = 10; P < 0.05). Our data indicate that the modulation of K(ir) seems to be an essential pathway in the antagonistic effects of nicotine on bFGF-mediated endothelial cell growth, migration and NO-formation.
Kuhlmann
Christoph Rüdiger Wolfram
CR
Department of Cardiology and Angiology, Justus-Liebig-University of Giessen, Klinikstr. 36, 35392 Giessen, Germany. christoph.r.kuhlmann@innere.med.uni-giessen.de
Scharbrodt
Wolfram
W
Schaefer
Christian Alexander
CA
Most
Astrid Kerstin
AK
Backenköhler
Ulrich
U
Neumann
Thomas
T
Tillmanns
Harald
H
Waldecker
Bernd
B
Erdogan
Ali
A
Wiecha
Johannes
J
D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D004553:Electric Conductivity; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology
D016222:Fibroblast Growth Factor 2; D009538:Nicotine; D006152:Cyclic GMP; D011188:Potassium