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Differential Regulation of Cytoplasmic and Nucleoplasmic Calcium in Pulmonary Arterial Smooth Muscle Cells
Author(s) -
Cao YuanNing,
Yang XiaoRu,
Sham James S.K.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1440-a
Subject(s) - cytoplasm , cytosol , microbiology and biotechnology , calcium , vascular smooth muscle , chemistry , biology , biophysics , medicine , endocrinology , biochemistry , smooth muscle , organic chemistry , enzyme
Calcium ion is a ubiquitous signaling molecule, which exerts its diverse effects through global and local signaling in various subcellular compartments. In vascular smooth muscle cells, cytoplasmic Ca 2+ (cCa 2+ ) serves primarily for muscle contractions, whereas nucleoplasmic Ca 2+ (nCa 2+ ) is involved in gene regulation. Here we examined the regulations of cCa 2+ and nCa 2+ in rat pulmonary arterial smooth muscle cells (PASMCs) by using laser scanning confocal microscopy. Activation of voltage‐gated Ca 2+ channels by 60 mM KCl increased both cCa 2+ and nCa 2+ , with the rise in cCa 2+ consistently led the increase in nCa 2+ . A low concentration of endothelin‐1 (ET‐1) caused small sporadic cytosolic Ca 2+ oscillations, which failed to perturb nCa 2+ , suggesting that the nuclear envelope acts as a partial barrier for Ca 2+ diffusion. In contrast, platelet derived growth factor (100 ng/ml) elicited large oscillations in cCa 2+ and nCa 2+ with the increase in nCa 2+ usually preceded the cCa 2+ response, suggesting that the nucleoplasmic Ca 2+ stores are the initial sites activated by the growth factor. These differences in the kinetics of cCa 2+ and nCa 2+ transients clearly indicate a differential regulation of Ca 2+ in cytoplasmic and nucleoplasmic compartments that may be essential for the independent regulation of contraction and gene expression in PASMCs.