Volume- and calcium-activated chloride channels in human umbilical vein endothelial cells.
OBJECTIVE
To characterize the properties of chloride currents and its modulation in human umbilical vein endothelial cells (HUVEC).


METHODS
Using whole-cell patch-clamp recording techniques.


RESULTS
Exposure of HUVEC to 13.5% and 27% hypotonic solution (HTS) induced a current ICl, vol. This current was correlated with the changes in cell volume and showed a modest outward rectification. It was slowly inactivated at positive potential (> 50 mV), and it was time- and voltage-independent in kinetics. The current densities (pA/pF) were 20 +/- 3 (13.5% HTS) and 58 +/- 4 (27% HTS, n = 7), respectively at +100 mV test potential. Applying GTP gamma s (300 mumol.L-1) elicited a current similar to ICl, vol, while cAMP (0.5 mmol.L-1) had no effect on the current. Increase in [Ca2+]i, either by directly loading cells with high concentration of Ca2+ (CaCl2), or by perfusing vasoactive agonist ATP (10 mumol.L-1), activated ICl, Ca. The current density was only (23 +/- 5) pA/pF (n = 8 cells). Such current was slowly activated at positive potential, inactivated quickly at negative potential, and showed strong outward rectification. Both currents were inhibited by DIDS and verapamil. Challenging a cell with elevated [Ca2+]i and HTS activated ICl, vol on the top of ICl, Ca in the same cell, suggested co-existence of these two currents and that they were modulated by different ways. cAMP-regulated chloride channel and ClC (chloride channel family) channel were absent.


CONCLUSIONS
HUVEC express two kinds of chloride channels, ICl, vol activated by change in cell volume and ICl, Ca by elevation of [Ca2+]i, respectively.
Zhong
N
N
Physiological Laboratory of Hypoxia, Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai 200031, China. nolannz@sunm.shcnc.ac.cn
Fang
Q Z
QZ
Zhang
Y
Y
Zhou
Z N
ZN
D000255:Adenosine Triphosphate / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002469:Cell Separation; D048429:Cell Size; D018118:Chloride Channels / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D018408:Patch-Clamp Techniques; D014471:Umbilical Veins / Q000166:cytology; D014700:Verapamil / Q000494:pharmacology
D018118:Chloride Channels; D000255:Adenosine Triphosphate; D014700:Verapamil; D000242:Cyclic AMP; D002118:Calcium