EGF suppresses hydrogen peroxide induced Ca2+ influx by inhibiting L-type channel activity in cultured human corneal endothelial cells.
Endogenous generated hydrogen peroxide during eye bank storage limits viability. We determined in cultured human corneal endothelial cells (HCEC) whether: (1) this oxidant induces elevations in intracellular calcium concentration [Ca2+]i; (2) epidermal growth factor (EGF) medium supplementation has a protective effect against peroxide mediated rises in [Ca2+]i. Whereas pathophysiological concentrations of H2O2 (10 mM) induced irreversible large increases in [Ca2+]i, lower concentrations (up to 1 mM) had smaller effects, which were further reduced by exposure to either 5 microM nifedipine or EGF (10 ng ml(-1)). EGF had a larger protective effect against H2O2-induced rises in [Ca2+]i than nifedipine. In addition, icilin, the agonist for the temperature sensitive transient receptor potential protein, TRPM8, had complex dose-dependent effects (i.e. 10 and 50 microM) on [Ca2+]i. At 10 microM, it reversibly elevated [Ca2+]i whereas at 50 microM an opposite effect occurred suggesting complex effects of temperature on endothelial viability. Taken together, H2O2 induces rises in [Ca2+]i that occur through increases in Ca2+ permeation along plasma membrane pathways that include L-type Ca2+ channels as well as other EGF-sensitive pathways. As EGF overcomes H2O2-induced rises in [Ca2+]i, its presence during eye bank storage could improve the outcome of corneal transplant surgery.
Mergler
Stefan
S
Medizinische Klinik m. S. Hepatologie und Gastroenterologie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, D-13353 Berlin, Germany. stefan.mergler@charite.de
Pleyer
Uwe
U
Reinach
Peter
P
Bednarz
Jürgen
J
Dannowski
Haike
H
Engelmann
Katrin
K
Hartmann
Christian
C
Yousif
Tarik
T
D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D002460:Cell Line; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004728:Endothelium, Corneal / Q000187:drug effects* / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016877:Oxidants / Q000037:antagonists & inhibitors / Q000494:pharmacology
D020746:Calcium Channels, L-Type; D016877:Oxidants; D004815:Epidermal Growth Factor; D006861:Hydrogen Peroxide; D002118:Calcium