EXCEED THE SPACE PROVIDED. Local Ca2+ release transients, or 'Ca2+ sparks', originated from ryanodine receptors on sarcoplasmic receptors have been identified in cardiac, skeletal, and smooth muscles. In systemic vascular smooth muscles, they have been implicated as a feedback modulator of membrane potential by increasing local [Ca2+], activating nearby Ca2+-activated K+ (KCa) channels, leading to membrane hyperpolarization and vasodilation. Recently, we have identified and characterized Ca2+ sparks in rat intralobar pulmonary arterial smooth muscle cells (PASMCs). In contrast to systemic vascular smooth muscle, activation of Ca2+ spark in PASMCs causes membrane depolarization. Endothelin-1 (ET-1), a major mediator of acute and chronic hypoxia induced pulmonary vasoconstriction, causes dramatic increase in Ca2+ spark frequency, which can be blocked by ET-A receptor antagonist, and non-selective cation channels. Inhibition of Ca2+ sparks with ryanodine significantly attenuated the ET-1 induced contraction of pulmonary arteries. Enhancement of Ca2+ spark by ET-1 is evident even at a threshold concentration (10-10 M), which at the best cause minimal contraction but is capable of potentiating hypoxic pulmonary vasoconstriction and contraction induced by other vasoconstrictor. Moreover, norepinephrine, which activates the PLC/PKC pathway similar to ET-1, causes the opposite effect of inhibiting Ca2+ sparks in PASMCs. Based on these novel findings, we propose that Ca2+ spark in PASMCs promote vasoconstriction, and vasoconstrictors modulate Ca2+ sparks through specific receptor dependent mechanisms. To test this hypotheses, we will apply a combination of state-of-the-art techniques including whole-cell patch clamp, laser-scanning confocal microscopy, and UV-pulse laser flash photolysis, RT-PCR, and gene-knockout with antisense oligonucleotide to examine if Ca2+ spark of PASMCs promotes vasoconstriction by (i) inducing membrane depolarization, (ii) providing Ca2+ for direct myofilament activation, and/or (iii) potentiating the contractile effects of other physiological stimuli. We will also characterize and identify signaling pathways for agonist- induced Ca2+ sparks activation, and determine the molecular identity and functional role of non-selective cation channels in Ca2+ spark actiivation. This project will provide important information on the unique control of pulmonary circulation by subcellular local Ca2+ signaling. PERFORMANCE SITE ========================================Section End===========================================

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL071835-03
Application #
6824048
Study Section
Lung Biology and Pathology Study Section (LBPA)
Program Officer
Denholm, Elizabeth M
Project Start
2002-12-15
Project End
2006-11-30
Budget Start
2004-12-01
Budget End
2005-11-30
Support Year
3
Fiscal Year
2005
Total Cost
$327,000
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
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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
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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
Balasubramanian, Lavanya; Lo, Chun-Min; Sham, James S K et al. (2013) Remanent cell traction force in renal vascular smooth muscle cells induced by integrin-mediated mechanotransduction. Am J Physiol Cell Physiol 304:C382-91
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

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