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Dose‐Dependent Activation of Ca 2+ ‐Activated K + Channels by Ethanol Contributes to Improved Endothelial Cell Functions
Author(s) -
Kuhlmann Christoph R. W.,
Li Fang,
Lüdders Dörte W.,
Schaefer Christian A.,
Most Astrid K.,
Backenköhler Ulrich,
Neumann Thomas,
Tillmanns Harald,
Waldecker Bernd,
Erdogan Ali,
Wiecha Johannes
Publication year - 2004
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1097/01.alc.0000130811.92457.0d
Subject(s) - chemistry , umbilical vein , pertussis toxin , iberiotoxin , calcium , endothelial stem cell , liter , nitric oxide , endocrinology , ethanol , medicine , biochemistry , biology , signal transduction , g protein , in vitro
Background: Regular moderate alcohol (EtOH) intake seems to protect against both coronary artery disease and ischemic stroke, whereas the risk increases with heavy EtOH consumption. Effects of EtOH on endothelial cell function may be relevant to these disparate effects. Potassium channels play an important role in the regulation of endothelial cell functions. Therefore, we investigated whether Ca 2+ ‐activated K + channels (BK Ca ) are modulated by EtOH. Furthermore, we examined whether EtOH‐induced changes of endothelial nitric oxide (NO) formation and cell proliferation are due to BK Ca activation. Methods: The patch‐clamp technique was used to investigate BK Ca activity in cultured human umbilical vein endothelial cells (HUVEC). NO formation was analyzed by using the fluorescence dye 4,5‐diaminofluorescein. Endothelial proliferation was examined by using cell counts and measuring [ 3 H]thymidine incorporation. Results: EtOH dose‐dependently (10–150 mmol/liter) modulated BK Ca ‐activity, with the highest increase of open‐state probability at a concentration of 50 mmol/liter ( n = 13; p < 0.05). Inside‐out recordings revealed that this effect was due to direct BK Ca activation, whereas open‐state probability was not changed in cell‐attached recordings after pertussis toxin preincubation. EtOH (10 and 50 mmol/liter) caused a significant increase of NO levels, which was blocked by the highly selective BK Ca inhibitor iberiotoxin (100 nmol/l; n = 30; p < 0.05). Higher concentrations of EtOH (100 and 150 mmol/liter) significantly reduced NO synthesis ( n = 30; p < 0.05). Both methods revealed a significant increase of HUVEC proliferation, which was inhibited by iberiotoxin ( n = 30; p < 0.05). At a concentration of 150 mmol/liter, EtOH caused a significant reduction of endothelial proliferation. Conclusions: EtOH directly activates BK Ca in HUVEC, leading to an increase of endothelial proliferation and production of NO. These results indicate a possible beneficial effect of low‐dose EtOH on endothelial function, whereas higher concentrations must be considered as harmful.