Vascular endothelial growth factor inhibits outward delayed-rectifier potassium currents in acutely isolated hippocampal neurons.
In the present study, whole-cell patch-clamp recording was used to study whether vascular endothelial growth factor (VEGF) had a regulatory effect on the potassium-channel currents. The outward delayed-rectifier potassium currents (I(K)) were recorded in acutely isolated hippocampal neurons from 14-day-old rat brains. A local application of VEGF at the concentrations from 50 ng/ml to 200 ng/ml dose-dependently inhibited I(K). Administration of VEGF (100 ng/ml) to the neurons only for seconds could significantly reduce I(K) in 26 of 39 recorded cells. The currents could recover to 82.8+/-3.7% of the control level at 60 s after removing VEGF in the buffer. In the I-V curve analysis, VEGF negatively shifted the I-V curve of I(K); the inhibition was gradually enhanced as the membrane potential increased from -40 mV to 50 mV in 13 cells. Thus, the results reveal that VEGF inhibits I(K) in acute, reversible and voltage-dependent manners. Double staining combined with confocal laser scanning microscopy was used to simultaneously detect the distribution of VEGF receptors (flt-1 and flk-1) in the hippocampal section and isolated neuron. Results showed that flt-1-positive staining, but not flk-1, could be observed on the membrane of the hippocampal neuron in both preparations, suggesting the presence of neuronal membrane VEGF flt-1 receptors in the hippocampus. To investigate if the inhibition by VEGF on I(K) is related to the presence of flt-1 receptors, we further did flt-1-receptor immunostaining for the recorded neurons, which was labeled with Lucifer Yellow during the recording. Among nine recorded cells, five showing the inhibition by VEGF had detectable signals for flt-1 receptors on their membrane, whereas the other four showing no inhibition had no flt-1 receptors either. The results suggest that VEGF can acutely inhibit I(K) in the hippocampal neurons probably related to the presence of membrane flt-1 receptors in the neurons.
Xu
J Y
JY
National Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, 138 Yi-Xue-Yuan Road, 200032, P.R., Shanghai, China.
Zheng
P
P
Shen
D H
DH
Yang
S Z
SZ
Zhang
L M
LM
Huang
Y L
YL
Sun
F-Y
FY
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016228:Endothelial Growth Factors / Q000378:metabolism / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism / Q000494:pharmacology*; D008222:Lymphokines / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D018613:Microscopy, Confocal; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000187:drug effects / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000187:drug effects / Q000378:metabolism; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D015221:Potassium Channels; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2