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PKC Inhibition Restores Store‐Operated Ca 2+ Entry in Pulmonary Endothelial Cells From Chronically Hypoxic Rats
Author(s) -
Paffett Michael L,
Resta Thomas C,
Walker Benjimen R
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.a860-b
Subject(s) - protein kinase c , agonist , diacylglycerol kinase , endocrinology , medicine , gene isoform , chemistry , hypoxia (environmental) , receptor , pharmacology , biology , kinase , biochemistry , oxygen , organic chemistry , gene
Chronic hypoxia (CH)‐induced pulmonary hypertension is associated with decreased basal pulmonary artery endothelial cell (EC) Ca 2+ which correlates with reduced store‐operated Ca 2+ (SOC) entry. Protein kinase C (PKC) has been postulated to attenuate SOC entry in ECs. Therefore, we hypothesized that PKC has a greater inhibitory effect on EC SOC entry following CH. To test this hypothesis, we assessed different modes of Ca 2+ entry in the presence or absence of the PKC inhibitor GF109203X (1 μM) in freshly isolated, fura‐2 loaded ECs obtained from rats exposed to 4 weeks of hypobaric hypoxia. Consistent with our hypothesis, we found that PKC inhibition restored SOC entry following CH to control levels. Additional experiments were performed in which Ca 2+ entry in response to the diacylglycerol analog 1‐Oleoyl‐2‐acetyl‐sn‐glycerol (OAG) was measured in non‐store depleted ECs. No differences were detected in OAG‐induced entry between control and CH ECs, and PKC inhibition augmented the response similarly between groups. We also assessed agonist‐induced Ca 2+ entry with 20 μM ATP ± GF109203X. We observed reduced agonist‐induced Ca 2+ entry in ECs from CH rats compared to controls; however PKC inhibition impaired the Ca 2+ response in the control group only. We conclude that SOC and agonist‐induced Ca 2+ entry are regulated by PKC, however various PKC isoforms may differentially affect Ca 2+ entry following CH.