Calcium Channels in Neonatal Pulmonary Hypertension

描述（由申请人提供）：本试验项目的目的是确定电压门控L型Ca 2+（CaL）通道在新生儿肺动脉高压（PH）发病机制中的作用。使用新生仔猪缺氧诱导PH的良好模型，体内血流动力学显示暴露于慢性缺氧（CH）21天的新生仔猪静息肺张力增加。在离体的，灌注肺从相同的CH仔猪的研究表明，硝苯地平敏感的CaL，通道有助于异常的血管紧张度，和CaL电流密度升高，观察到在膜片钳血管平滑肌细胞从小肺动脉。随后的研究揭示了CH仔猪肺血管中CaL通道的成孔α 1C亚基的显著上调，这对应于促进CaL通道运输的辅助p2 a亚基的表达增加。有趣的是，血栓素A2和内皮素-1在培养的小肺动脉中诱导了相同的CaL通道异常模式，这两种血管收缩物质与新生儿PH有关。预防性治疗，以降低血栓素A2的可用性21-CH日龄仔猪阻止了肺血管中CaL通道的上调，并减轻了PH的发展。血管收缩物质对CaL通道的上调导致新生儿PH，我们将致力于实现以下特定目标：（a）鉴定新生仔猪的小肺动脉中CaL通道的分子组成，（B）确定血栓素A2和内皮素-1上调CH仔猪的小肺动脉中CaL通道的机制基础，和（c）确定血栓素A2和内皮素-1是否在体内上调肺血管中的CaL通道以促进PH的发展。这些研究将提供有关促进异常CaL通道表达的刺激和机制的第一个详细信息新生儿PH期间肺血管系统，并将有助于确定治疗目标，以减轻婴儿和幼儿的PH。

DESCRIPTION (provided by applicant): The goal of this pilot project is to define the contribution of voltage-gated, L-type Ca2+ (CaL) channels to the pathogenesis of pulmonary hypertension (PH) in the neonate. Using a well established model of hypoxia-induced PH in neonatal piglets, in-vivo hemodynamics revealed an increased resting pulmonary tone in neonatal piglets exposed to chronic hypoxia (CH) for 21 days. Studies in isolated, perfused lungs from the same CH piglets demonstrated that nifedipine-sensitive CaL, channels contributed to the anomalous vascular tone, and an elevated density of CaL current was observed in patch-clamped vascular smooth muscle cells from small pulmonary arteries. Subsequent studies revealed a striking upregulation of the pore-forming alpha1C subunit of the CaL channel in the pulmonary vasculature of CH piglets, which corresponded to an increased expression of the ancillary p2a subunit that promotes CaL channel trafficking. Interestingly, this same pattern of CaL channel abnormalities was induced in cultured small pulmonary arteries by thromboxane A2 and endothelin-1, two vasoconstrictor substances implicated in neonatal PH. Finally, prophylactic therapy to lower thromboxane A2 availability in 21-day CH piglets prevented the upregulation of CaL channels in the pulmonary vasculature and mitigated the development of PH. Based on these key findings suggesting that the upregulation of CaL channels by vasoconstrictor substances contributes to neonatal PH, we will pursue specific aims designed to: (a) identify the molecular composition of CaL channels in small pulmonary arteries of neonatal piglets, (b) define the mechanistic basis by which thromboxane A2 and endothelin-1 upregulate CaL channels in small pulmonary arteries of CH piglets, and (c) determine if thromboxane A2 and endothelin-1 upregulate CaL channels in the pulmonary vasculature in vivo to contribute to the development of PH. These studies will provide the first detailed information on the stimuli and mechanisms that promote abnormal CaL, channel expression in the pulmonary vasculature during neonatal PH, and will assist in identifying therapeutic targets to mitigate PH in infants and young children.