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Cholesterol regulates both store‐ and agonist‐induced Ca 2+ entry in pulmonary arterial endothelium (1089.9)
Author(s) -
Zhang Bojun,
Riddle Melissa,
Naik Jay,
Resta Thomas,
Walker Benjimen
Publication year - 2014
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.28.1_supplement.1089.9
Subject(s) - chemistry , agonist , cyclopiazonic acid , endocrinology , endothelium , medicine , filipin , endoplasmic reticulum , cholesterol , biochemistry , biology , receptor
Endothelial Ca 2+ entry is decreased in pulmonary arteries from rats exposed to chronic hypoxia (CH) (4 wk, PB = 380 torr). In addition, membrane cholesterol (Chol) is diminished in these cells and Chol supplementation restores ATP‐induced Ca 2+ entry. Since both agonist‐induced and store‐operated Ca 2+ entry (SOCE) are decreased after CH, we hypothesized that both require functional membrane Chol. To test this hypothesis, we administered epicholesterol (EpiCh; epimeric form of cholesterol) or vehicle to pulmonary arterial endothelial cells (PAEC) from control and CH rats to replace native Chol. The efficacy of EpiCh to diminish membrane Chol was confirmed by filipin staining in cultured ECs. EpiCh treatment greatly reduced both cyclopiazonic acid (CPA) ‐induced SOCE and ATP‐induced Ca 2+ entry in PAECs from control and CH rats. We next assessed the effect of EpiCh on ATP and CPA‐induced Ca 2+ currents in PAEC from control rats using patch clamp. Both EpiCh and La 3+ inhibited ATP‐induced current similarly. Although T‐type voltage gated Ca 2+ channels contribute to ATP responses, mibefradil (T‐type inhibitor) had no further effect in EpiCh treated cells. Likewise, CPA‐induced current was reduced in cells treated with EpiCh. We conclude that membrane Chol is required for both agonist‐induced and store‐operated Ca 2+ entry in PAEC and that reduced Ca 2+ seen after CH is possibly due to loss of this key regulator. Grant Funding Source : Supported by NIH grant HL95640