Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL, USA.
Department of Anesthesiology, Banner-University Medical Center, University of Arizona College of Medicine, Suite 4401, 1501 N. Campbell Avenue, Tucson, AZ, 85724-5114, USA.
Cardiovasc Eng Technol. 2020 Dec;11(6):655-662. doi: 10.1007/s13239-020-00489-5. Epub 2020 Oct 1.
Acute increases in hydrostatic pressure activate endothelial signaling pathways that modulate barrier function and vascular permeability. We investigated the role the glycocalyx and established mechanotransduction pathways in pressure-induced albumin transport across rat lung microvascular endothelial cells.
Rat lung microvascular endothelial cells (RLMEC) were cultured on Costar Snapwell chambers. Cell morphology was assessed using silver nitrate staining. RLMEC were exposed to zero pressure (Control) or 30 cmHO (Pressure) for 30 or 60 min. Intracellular albumin uptake and transcellular albumin transport was quantified. Transcellular transport was reported as solute flux (J) and an effective permeability coefficient (P). The removal of cell surface heparan sulfates (heparinase), inhibition of NOS (L-NAME) and reactive oxygen species (apocynin, Apo) was investigated.
Acute increase in hydrostatic pressure augmented albumin uptake by 30-40% at 60 min and J and P both increased significantly. Heparinase increased albumin uptake but attenuated transcellular transport while L-NAME attenuated both pressure-dependent albumin uptake and transport. Apo interrupted albumin uptake under both control and pressure conditions, leading to a near total lack of transcellular transport, suggesting a different mechanism and/or site of action.
Pressure-dependent albumin uptake and transcellular transport is another component of endothelial mechanotransduction and associated regulation of solute flux. This novel albumin uptake and transport pathway is regulated by heparan sulfates and eNOS. Albumin uptake is sensitive to ROS. The physiological and clinical implications of this albumin transport are discussed.
静水压力的急性增加会激活内皮细胞信号通路，调节屏障功能和血管通透性。我们研究了糖萼和已建立的机械转导途径在压力诱导的大鼠肺微血管内皮细胞（RLMEC）白蛋白跨细胞转运中的作用。
在 Costar Snapwell 室中培养大鼠肺微血管内皮细胞（RLMEC）。使用硝酸银染色评估细胞形态。将 RLMEC 暴露于零压力（对照）或 30cmH2O（压力）下 30 或 60min。定量测定细胞内白蛋白摄取和跨细胞白蛋白转运。跨细胞转运以溶质通量（J）和有效渗透系数（P）表示。研究了细胞表面肝素硫酸盐（肝素酶）的去除、NOS 抑制（L-NAME）和活性氧物质（apocynin，Apo）的抑制作用。
急性增加静水压力可在 60min 时使白蛋白摄取增加 30-40%，J 和 P 均显著增加。肝素酶增加白蛋白摄取，但减弱跨细胞转运，而 L-NAME 减弱压力依赖性白蛋白摄取和转运。Apo 在对照和压力条件下均中断白蛋白摄取，导致跨细胞转运几乎完全缺失，提示存在不同的作用机制和/或作用部位。
压力依赖性白蛋白摄取和跨细胞转运是内皮细胞机械转导和相关溶质通量调节的另一个组成部分。这种新的白蛋白摄取和转运途径受肝素硫酸盐和 eNOS 调节。白蛋白摄取对 ROS 敏感。讨论了这种白蛋白转运的生理和临床意义。
