Effects of cyanide and deoxyglucose on Ca2+ signalling in macrovascular endothelial cells.
1. We have studied the effects of the metabolic inhibitors cyanide (CN) and deoxyglucose (DG) on the intracellular Ca2+ concentration ([Ca2+]i) in macrovascular endothelial cells derived from human umbilical vein (EA cells). 2. CN- and DG increased [Ca2-]i in non-voltage clamped cells. This effect was dependent on extracellular Ca2+ concentration and membrane potential, indicating that CN- induced a Ca2+ entry. 3. During expose to CN- and/or DG, EA cells depolarise. This depolarisation is sometimes preceded by a small, but transient hyperpolarisation due to activation of a big - conductance K+ channels, BKCa, present in EA cells. However, in approximately 90% of the cells tested, the CN- and/or DG induced elevation of [Ca2+]i was insufficient to activate BKCa. 4. CN- and/or DG enhanced BKCa currents preactivated by an elevation of [Ca2+]i via cell dialysis with 0.5 and 1 microM, respectively. Thus, metabolic inhibition sensitises BKCa. 5. The CN- induced depolarisation of EA cells occurs by activating a current that reversed at positive membrane potentials. Substituting extracellular cations abolished the inward component of this current by NMDG, indicating that CN- activated a non-selective cation channel, NSC. This current was reduced by extracellular Ca2+ and Mg2'+ but is partially carried by Ca2+. 6. It is concluded that CN elevates [Ca2+]i by activating Ca2+ permeable NSC channels. The properties of these channels are similar to those of the recently described trp3 channels expressed in endothelium.
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Katholieke Universiteit Leuven, Laboratorium voor Fysiologie, Campus Gasthuisberg, Belgium.
Droogmans
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Nilius
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B
D000963:Antimetabolites / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D002460:Cell Line; D003486:Cyanides / Q000494:pharmacology*; D003847:Deoxyglucose / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism
D000963:Antimetabolites; D003486:Cyanides; D007473:Ion Channels; D015221:Potassium Channels; D003847:Deoxyglucose