Published online before print June 8, 2006, doi: 10.1161/01.ATV.0000231518.86795.0f
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© 2006 American Heart Association, Inc.
Vascular Biology |
VEGF Activates Receptor-Operated Cation Channels in Human Microvascular Endothelial Cells
From the Microvascular Research Laboratories (H.W.-C., R.R.F., D.O.B.) and Cardiovascular Research Laboratories (H.W.-C., A.F.J., J.C.H.), Department of Physiology, University of Bristol, UK.
Correspondence to Dr David Bates, Microvascular Research Laboratories, Department of Physiology, Preclinical Veterinary School, University of Bristol, Southwell St, Bristol BS2 8EJ, UK. E-mail Dave.Bates{at}bristol.ac.uk; or Prof Jules Hancox, Cardiovascular Research Laboratories and Department of Physiology, School of Medical Sciences, University Walk, Bristol, BS8 1TD, UK. E-mail Jules.Hancox@bristol.ac.uk
Objective— Vascular endothelial growth factor (VEGF) exerts many of its effects by stimulating endothelial calcium influx, but little is known about channels mediating VEGF-induced cation entry. The aim of this study was to measure and characterize for the first time the VEGF-activated cation current in human microvascular endothelial cells (HMVECs).
Methods and Results— Whole-cell patch-clamp recordings were made from HMVECs. During applied voltage ramps, VEGF activated a current that reversed at 0 mV, was sensitive to gadolinium, and required extracellular cations. Noise analysis yielded a single-channel conductance of 27 pS. The current was not dependent on intracellular calcium stores, and was not blocked by inositol triphosphate (IP3) receptor or serine/threonine kinase inhibition but was partially inhibited by flufenamic acid. A similar current was activated by 1-oleoyl-2-acetyl-sn-glycerol (OAG), a membrane-permeant analog of diacylglycerol (DAG). To determine whether VEGF could activate recombinant ion channels with similar properties, we investigated the effect of VEGF on Chinese hamster ovary cells cotransfected with VEGFR2 and the canonical transient receptor potential (TRPC) channels, TRPC3 or TRPC6. VEGF induced a similar current to that described above in VEGFR2-TRPC3 and VEGFR2-TRPC6 cells but not in cells transfected with either cDNA alone.
Conclusions— VEGF activates a receptor-operated cation current in HMVECs and OAG can activate directly a similar current in these cells. VEGF is also able to activate heterologously expressed TRPC3/6 channels through VEGFR2.
In human microvascular endothelial cells, VEGF activated a 27 pS, gadolinium-sensitive cation current, reversing at 0 mV, that was independent of calcium stores, IP3 receptors, or serine/threonine kinases. A similar current was activated by OAG and, in VEGFR2-TRPC3– and VEGFR2-TRPC6–transfected cells, by VEGF. VEGF activates a receptor-operated cation channel.
Key Words: VEGF • vascular permeability • ROC • endothelium
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