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Neutral sphingomyelinase, NADPH oxidase and reactive oxygen species. Role in acute hypoxic pulmonary vasoconstriction
Author(s) -
Frazziano Giovanna,
Moreno Laura,
MoralSanz Javier,
Menendez Carmen,
Escolano Lucía,
Gonzalez Constancio,
Villamor Eduardo,
AlvarezSala Jose Luis,
Cogolludo Angel L.,
PerezVizcaino Francisco
Publication year - 2011
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.22611
Subject(s) - apocynin , nadph oxidase , hypoxic pulmonary vasoconstriction , reactive oxygen species , mitochondrial ros , protein kinase c , hypoxia (environmental) , ceramide , microbiology and biotechnology , vasoconstriction , sphingomyelin phosphodiesterase , phosphorylation , chemistry , biology , biochemistry , endocrinology , oxygen , apoptosis , organic chemistry
The molecular mechanisms underlying hypoxic pulmonary vasoconstriction (HPV) are not yet properly understood. Mitochondrial electron transport chain (ETC) and NADPH oxidase have been proposed as possible oxygen sensors, with derived reactive oxygen species (ROS) playing key roles in coupling the sensor(s) to the contractile machinery. We have recently reported that activation of neutral sphingomyelinase (nSMase) and protein kinase C ζ (PKCζ) participate in the signalling cascade of HPV. Herein, we studied the significance of nSMase in controlling ROS production rate in rat pulmonary artery (PA) smooth muscle cells and thereby HPV in rat PA. ROS production (analyzed by dichlorofluorescein and dihydroethidium fluorescence) was increased by hypoxia in endothelium‐denuded PA segments and their inhibition prevented hypoxia‐induced voltage‐gated potassium channel (K V ) inhibition and pulmonary vasoconstriction. Consistently, H 2 O 2 , or its analogue t ‐BHP, decreased K V currents and induced a contractile response, mimicking the effects of hypoxia. Inhibitors of mitochondrial ETC (rotenone) and NADPH oxidase (apocynin) prevented hypoxia‐induced ROS production, K V channel inhibition and vasoconstriction. Hypoxia induced p47 phox phosphorylation and its interaction with caveolin‐1. Inhibition of nSMase (GW4869) or PKCζ prevented p47 phox phosphorylation and ROS production. The increase in ceramide induced by hypoxia (analyzed by immunocytochemistry) was inhibited by rotenone. Exogenous ceramide increased ROS production in a PKCζ sensitive manner. We propose an integrated signalling pathway for HPV which includes nSMase‐PKCζ‐NADPH oxidase as a necessary step required for ROS production and vasoconstriction. J. Cell. Physiol. 226: 2633–2640, 2011. © 2010 Wiley‐Liss, Inc.