Kitagawa Melanie G, Reynolds Julia O, Durgan David, Rodney George, Karmouty-Quintana Harry, Bryan Robert, Pandit Lavannya M
Baylor College of Medicine, Houston, Texas.
Texas Children's Hospital, Houston, Texas.
Physiol Rep. 2019 Jan;7(1):e13950. doi: 10.14814/phy2.13950.
We have previously shown Twik-2 mice develop pulmonary hypertension and vascular remodeling. We hypothesized that distal pulmonary arteries (D-PAs) of the Twik-2 mice are hypercontractile under physiological venous conditions due to altered electrophysiologic properties between the conduit and resistance vessels in the pulmonary vascular bed. We measured resting membrane potential and intracellular calcium through Fura-2 in freshly digested pulmonary artery smooth muscles (PASMCs) from both the right main (RM-PA) and D-PA (distal) regions of pulmonary artery from WT and Twik-2 mice. Whole segments of RM-PAs and D-PAs from 20 to 24-week-old wildtype (WT) and Twik-2 mice were also pressurized between two glass micropipettes and bathed in buffer with either arterial or venous conditions. Abluminally-applied phenylephrine (PE) and U46619 were added to the buffer at log increments and vessel diameter was measured. All values were expressed as averages with ±SEM. Vasoconstrictor responses did not differ between WT and Twik-2 RM-PAs under arterial conditions. Under venous conditions, Twik-2 RM-PAs showed an increased sensitivity to PE with a lower EC50 (P = 0.02). Under venous conditions, Twik-2 D-PAs showed an increase maximal vasoconstrictor response to both phenylephrine and U46619 compared to the WT mice (P < 0.05). Isolated PASMCs from Twik-2 D-PA were depolarized and had higher intracellular calcium levels compared to PASMCs from RM-PA of both WT and Twik-2 mice. These studies suggest that hypercontractile responses and electrophysiologic properties unique to the anatomic location of the D-PAs may contribute to pulmonary hypertensive vasculopathy.
我们之前已表明，Twik - 2小鼠会发生肺动脉高压和血管重塑。我们推测，由于肺血管床中输送血管和阻力血管之间电生理特性的改变，Twik - 2小鼠的远端肺动脉（D - PA）在生理静脉条件下具有过度收缩性。我们通过Fura - 2测量了野生型（WT）和Twik - 2小鼠肺动脉右主支（RM - PA）和D - PA（远端）区域新鲜消化的肺动脉平滑肌细胞（PASMCs）的静息膜电位和细胞内钙。来自20至24周龄野生型（WT）和Twik - 2小鼠的RM - PA和D - PA的整个节段也在两个玻璃微吸管之间加压，并置于具有动脉或静脉条件的缓冲液中。以对数增量向缓冲液中添加腔外应用的去氧肾上腺素（PE）和U46619，并测量血管直径。所有值均表示为平均值±标准误。在动脉条件下，WT和Twik - 2 RM - PA之间的血管收缩反应没有差异。在静脉条件下，Twik - 2 RM - PA对PE的敏感性增加，EC50较低（P = 0.02）。在静脉条件下，与WT小鼠相比，Twik - 2 D - PA对去氧肾上腺素和U46619的最大血管收缩反应均增加（P < 0.05）。与WT和Twik - 2小鼠RM - PA的PASMCs相比，来自Twik - 2 D - PA的分离PASMCs去极化且细胞内钙水平更高。这些研究表明，D - PA解剖位置特有的过度收缩反应和电生理特性可能导致肺动脉高压性血管病变。
