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Acute hypoxia increases intracellular L‐arginine content in cultured porcine pulmonary artery endothelial cells
Author(s) -
Su Yunchao,
Block Edward R.
Publication year - 1996
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/(sici)1097-4652(199605)167:2<349::aid-jcp20>3.0.co;2-1
Subject(s) - arginine , calpain , intracellular , hypoxia (environmental) , nitric oxide , proteolysis , biochemistry , biology , arginase , microbiology and biotechnology , chemistry , endocrinology , enzyme , amino acid , oxygen , organic chemistry
Exposure to hypoxia (0% O 2 ) for 4–24 h resulted in increased intracellular L‐arginine content and increased activity of calpain, a calcium‐dependent neutral cysteine protease, in pulmonary artery endothelial cells. Calpain‐inhibitor I abolished the increased L‐arginine content in hypoxic cells. When endothelial cell proteins were labeled with [ 3 H]‐L‐arginine and the cells exposed to hypoxia, we observed an increase in free [ 3 H]‐L‐arginine and a decrease in [ 3 H]‐L‐arginine‐labeled proteins. Once again, calpain‐inhibitor I prevented the increases in free [ 3 H]‐L‐arginine and the decreases in [ 3 H]‐L‐arginine‐labeled proteins in hypoxic cells. Hypoxia also inhibited the synthesis of L‐arginine‐containing proteins. Thus, the increase in intracellular L‐arginine content in hypoxic pulmonary artery endothelial cells is caused by an increase in proteolysis secondary to calpain and a decrease in protein synthesis. These results indicate that hypoxia can modulate the availability of free intracellular L‐arginine, the exclusive precursor of nitric oxide (NO) and the primary substrate of NO synthase, by affecting the synthesis and degradation of cellular proteins. © 1996 Wiley‐Liss, Inc.