Lakshminarayanan S, Antonetti D A, Gardner T W, Tarbell J M
Pennsylvania State University, Biomolecular Transport Dynamics Laboratory, Department of Chemical Engineering, University Park, Pennsylvania, USA.
Invest Ophthalmol Vis Sci. 2000 Dec;41(13):4256-61.
Vascular endothelial growth factor (VEGF) increases microvascular permeability in vivo and has been hypothesized to play a role in plasma leakage in diabetic retinopathy. Few controlled studies have been conducted to determine the mechanism underlying the effect of VEGF on transport properties (e.g., hydraulic conductivity [Lp]). This study was conducted to determine the effect of VEGF on bovine retinal microvascular endothelial LP and the role of nitric oxide (NO) and the guanylate cyclase/guanosine 3', 5'-cyclic monophosphate/protein kinase G (GC/cGMP/PKG) pathway downstream of NO in mediating the VEGF response.
Bovine retinal microvascular endothelial cells (BRECs) were grown on porous polycarbonate filters, and water flux across BREC monolayers in response to a pressure differential was measured to determine endothelial LP RESULTS: VEGF (100 ng/ml) increased endothelial LP: within 30 minutes of addition and by 13.8-fold at the end of 3 hours of exposure. VEGF stimulated endothelial monolayers to release NO and incubation of the BRECs with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA; 100 microM) significantly attenuated the VEGF-induced LP increase. It was observed that incubation of the monolayers with the GC inhibitor LY-83583 (10 microM) did not alter the VEGF-mediated LP: response. Addition of the cGMP analogue 8-br-cGMP (1 mM) did not change the baseline LP over 4 hours. Also, the PKG inhibitor KT5823 (1 microM) did not inhibit the response of BREC LP to VEGF.
These experiments indicate that VEGF elevates hydraulic conductivity in BRECs through a signaling mechanism that involves NO but not the GC/cGMP/PKG pathway.
血管内皮生长因子（VEGF）可增加体内微血管通透性，并且据推测其在糖尿病性视网膜病变的血浆渗漏中发挥作用。很少有对照研究来确定VEGF对转运特性（例如水力传导率[Lp]）产生影响的潜在机制。本研究旨在确定VEGF对牛视网膜微血管内皮细胞Lp的影响，以及一氧化氮（NO）和NO下游的鸟苷酸环化酶/鸟苷3'，5'-环磷酸/蛋白激酶G（GC/cGMP/PKG）途径在介导VEGF反应中的作用。
将牛视网膜微血管内皮细胞（BRECs）培养在多孔聚碳酸酯滤膜上，测量跨BRECs单层的水通量以响应压力差，从而确定内皮细胞Lp。
VEGF（100 ng/ml）增加了内皮细胞Lp：添加后30分钟内增加，暴露3小时结束时增加了13.8倍。VEGF刺激内皮细胞单层释放NO，用一氧化氮合酶抑制剂N（G）-单甲基-L-精氨酸（L-NMMA；100 microM）孵育BRECs可显著减弱VEGF诱导的Lp增加。观察到用GC抑制剂LY-83583（10 microM）孵育单层并未改变VEGF介导的Lp反应。添加cGMP类似物8-br-cGMP（1 mM）在4小时内未改变基线Lp。此外，PKG抑制剂KT5823（1 microM）未抑制BRECs Lp对VEGF的反应。
这些实验表明，VEGF通过涉及NO但不涉及GC/cGMP/PKG途径的信号传导机制提高了BRECs中的水力传导率。
