Chronic hypoxia, as occurs in many pulmonary diseases, results in vascular myocyte proliferation and pulmonary hypertension. Pulmonary arterial smooth muscle cells (PASMCs) from animals of chronic hypoxia are associated with an elevated [Ca2+]i and altered reactivity to agonists, suggesting alterations in Ca2+ homeostasis intrinsic to PASMCs. It has been postulated that chronic hypoxia suppresses KV channel expression, leading to membrane depolarization, activation of L-type Ca2+ channels, and increase in [Ca2+]i. However, some studies found that inhibition of L-type Ca2+ channels was ineffective in reducing the elevated [Ca2+]i and vasomotor tone, suggesting additional Ca2+ pathway(s) may be involved. Recently, we have identified multiple TRPC channel isoforms (TRP1, TRP3, and TRP6) in rat intra-lobar PASMCs. Semi-quantitative RT-PCR analyses show that TRPC1 and TRPC6 mRNA level were increased in chronic hypoxic PASMCs; functional studies showed significant increase in store- and receptor-operated Ca2+ entry. In addition, we found that local Ca2+ release transients, """"""""Ca2+ sparks"""""""", have very robust interactions with IP3-receptors and TRPCs. Both spontaneous and agonist-evoked Ca2+ spark activities were altered in chronic hypoxic PASMCs. Based on these findings, we hypothesis that multiple Ca2+ influx and release pathways are altered by chronic hypoxia; the increase in cation entry via TRPCs, and alterations in SR Ca2+ release processes play major roles in the increase in basal [Ca2+]i and vasomotor tone, and the alterations in vascular reactivity. To test these hypotheses, we will apply a combination of state-of-the-art techniques including whole-cell patch clamp, laser-scanning confocal microscopy, UV-pulse laser flash photolysis, microarray analysis, antisense gene knockout and isolated microvessels to examine (i) changes in gene-expressions of various Ca2+ transporters, and the associated changes in vascular reactivity, (ii) changes in ryanodine- and IP3-receptors dependent Ca2+ release, (iii) alterations in store-operated and receptor-operated Ca2+ entries, and (iv) specific TRPC subtypes responsible for the elevated basal [Ca2+]i in PASMCs and vasomotor tone in pulmonary arteries of chronic hypoxic rats. This project will provide unique information on the subcellular Ca2+ signaling and homeostasis in pulmonary vasculatures in chronic hypoxia-induce pulmonary hypertension.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL075134-04
Application #
7185136
Study Section
Respiratory Physiology Study Section (RESP)
Program Officer
Golden, AL
Project Start
2004-03-08
Project End
2009-02-28
Budget Start
2007-03-01
Budget End
2009-02-28
Support Year
4
Fiscal Year
2007
Total Cost
$357,464
Indirect Cost
Name
Johns Hopkins University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Lin, Amanda H Y; Sun, Hui; Paudel, Omkar et al. (2016) Conformation of ryanodine receptor-2 gates store-operated calcium entry in rat pulmonary arterial myocytes. Cardiovasc Res 111:94-104
Lee, Suengwon; Paudel, Omkar; Jiang, Yongliang et al. (2015) CD38 mediates angiotensin II-induced intracellular Ca(2+) release in rat pulmonary arterial smooth muscle cells. Am J Respir Cell Mol Biol 52:332-41
Huang, Chun; Hu, Jinxing; Subedi, Krishna P et al. (2015) Extracellular Adenosine Diphosphate Ribose Mobilizes Intracellular Ca2+ via Purinergic-Dependent Ca2+ Pathways in Rat Pulmonary Artery Smooth Muscle Cells. Cell Physiol Biochem 37:2043-59
Subedi, Krishna P; Paudel, Omkar; Sham, James S K (2014) Detection of differentially regulated subsarcolemmal calcium signals activated by vasoactive agonists in rat pulmonary artery smooth muscle cells. Am J Physiol Cell Physiol 306:C659-69
Xia, Yang; Yang, Xiao-Ru; Fu, Zhenzhen et al. (2014) Classical transient receptor potential 1 and 6 contribute to hypoxic pulmonary hypertension through differential regulation of pulmonary vascular functions. Hypertension 63:173-80
Jiang, Yong-Liang; Lin, Amanda H Y; Xia, Yang et al. (2013) Nicotinic acid adenine dinucleotide phosphate (NAADP) activates global and heterogeneous local Ca2+ signals from NAADP- and ryanodine receptor-gated Ca2+ stores in pulmonary arterial myocytes. J Biol Chem 288:10381-94
Xia, Yang; Fu, Zhenzhen; Hu, Jinxing et al. (2013) TRPV4 channel contributes to serotonin-induced pulmonary vasoconstriction and the enhanced vascular reactivity in chronic hypoxic pulmonary hypertension. Am J Physiol Cell Physiol 305:C704-15
Liu, Xiao-Ru; Liu, Qing; Chen, Gai-Ying et al. (2013) Down-regulation of TRPM8 in pulmonary arteries of pulmonary hypertensive rats. Cell Physiol Biochem 31:892-904
Sun, Hui; Xia, Yang; Paudel, Omkar et al. (2012) Chronic hypoxia-induced upregulation of Ca2+-activated Cl- channel in pulmonary arterial myocytes: a mechanism contributing to enhanced vasoreactivity. J Physiol 590:3507-21
Yang, Xiao-Ru; Lin, Amanda H Y; Hughes, Jennifer M et al. (2012) Upregulation of osmo-mechanosensitive TRPV4 channel facilitates chronic hypoxia-induced myogenic tone and pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 302:L555-68

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