Program of Physiology and Biophysics, ICBM, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile.
Department of Anesthesiology, College of Physicians & Surgeons, Columbia University Medical Center, New York, NY, USA.
J Physiol. 2018 Jul;596(13):2491-2506. doi: 10.1113/JP274731. Epub 2018 May 23.
We investigated the excitation-contraction coupling mechanisms in small pulmonary veins (SPVs) in rat precision-cut lung slices. We found that SPVs contract strongly and reversibly in response to extracellular ATP and other vasoconstrictors, including angiotensin-II and endothelin-1. ATP-induced vasoconstriction in SPVs was associated with the stimulation of purinergic P2Y2 receptors in vascular smooth muscle cell, activation of phospholipase C-β and the generation of intracellular Ca oscillations mediated by cyclic Ca release events via the inositol 1,4,5-trisphosphate receptor. Active constriction of SPVs may play an important role in the development of pulmonary hypertension and pulmonary oedema.
The small pulmonary veins (SPVs) may play a role in the development of pulmonary hypertension and pulmonary oedema via active changes in SPV diameter, mediated by vascular smooth muscle cell (VSMC) contraction. However, the excitation-contraction coupling mechanisms during vasoconstrictor stimulation remain poorly understood in these veins. We used rat precision-cut lung slices and phase-contrast and confocal microscopy to investigate dynamic changes in SPV cross-sectional luminal area and intracellular Ca signalling in their VSMCs. We found that the SPV (∼150 μm in diameter) contract strongly in response to extracellular ATP and other vasoconstrictors, including angiotensin-II and endothelin-1. ATP-induced SPV contraction was fast, concentration-dependent, completely reversible upon ATP washout, and inhibited by purinergic receptor antagonists suramin and AR-C118925 but not by MRS2179. Immunofluorescence showed purinergic P2Y2 receptors expressed in SPV VSMCs. ATP-induced SPV contraction was inhibited by phospholipase Cβ inhibitor U73122 and accompanied by intracellular Ca oscillations in the VSMCs. These Ca oscillations and SPV contraction were inhibited by the inositol 1,4,5-trisphosphate receptor inhibitor 2-APB but not by ryanodine. The results of the present study suggest that ATP-induced vasoconstriction in SPVs is associated with the activation of purinergic P2Y2 receptors in VSMCs and the generation of Ca oscillations.
我们研究了大鼠离体肺切片中小肺静脉（SPV）的兴奋-收缩耦联机制。我们发现 SPV 对细胞外 ATP 和其他血管收缩剂（包括血管紧张素-II 和内皮素-1）强烈且可逆地收缩。SPV 中 ATP 诱导的血管收缩与血管平滑肌细胞中嘌呤能 P2Y2 受体的刺激、PLC-β 的激活以及通过肌醇 1,4,5-三磷酸受体介导的细胞内 Ca 震荡的产生有关。SPV 的主动收缩可能在肺动脉高压和肺水肿的发展中起重要作用。
小肺静脉（SPV）可能通过血管平滑肌细胞（VSMC）收缩导致 SPV 直径的主动变化，在肺动脉高压和肺水肿的发展中起作用。然而，在这些血管中，血管收缩剂刺激时的兴奋-收缩耦联机制仍知之甚少。我们使用大鼠离体肺切片和相差及共聚焦显微镜研究了 SPV 血管平滑肌细胞内的横截面管腔面积和细胞内 Ca 信号的动态变化。我们发现，直径约为 150μm 的 SPV 对细胞外 ATP 和其他血管收缩剂（包括血管紧张素-II 和内皮素-1）强烈收缩。ATP 诱导的 SPV 收缩迅速、浓度依赖性、ATP 洗脱后完全可逆，并被嘌呤能受体拮抗剂苏拉明和 AR-C118925 抑制，但不受 MRS2179 抑制。免疫荧光显示嘌呤能 P2Y2 受体在 SPV 血管平滑肌细胞中表达。PLCβ 抑制剂 U73122 抑制 ATP 诱导的 SPV 收缩，并伴有 VSMC 内的细胞内 Ca 震荡。这些 Ca 震荡和 SPV 收缩被肌醇 1,4,5-三磷酸受体抑制剂 2-APB 抑制，但不受肌醇 1,4,5-三磷酸受体抑制剂 2-APB 抑制。本研究结果表明，ATP 诱导的 SPV 血管收缩与 VSMC 中嘌呤能 P2Y2 受体的激活和 Ca 震荡的产生有关。
