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Regulation of Ca V 3.1 T‐type Ca 2+ channel expression by cAMP in pulmonary microvascular endothelial cells.
Author(s) -
Chen Hairu,
Zhou Chun,
Creighton Judy,
Sellak Hassan,
Wu Songwei
Publication year - 2006
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.20.4.a749-a
Subject(s) - agonist , endocrinology , medicine , guanine nucleotide exchange factor , patch clamp , protein kinase a , downregulation and upregulation , chemistry , microbiology and biotechnology , signal transduction , receptor , biology , kinase , biochemistry , gene
Activation of CaV3.1 T‐type Ca 2+ channel contributes to G q ‐linked agonist‐induced and store‐operated Ca 2+ entry in pulmonary microvascular endothelial cells (PMVECs). Since cAMP‐dependent pathways have been implicated in upregulation of ion channels including voltage‐gated Ca 2+ channels in excitable cells, we sought to examine whether a sustained elevation of cAMP increases the synthesis of Ca V 3.1 channels in endothelial cells. Cultured rat PMVECs were exposed to exogenous cAMP (pCPT‐cAMP 200 μM) for up to 96 hr and then subjected to whole‐cell patch‐clamp recordings to assess macroscopic T‐type currents. Using a two‐step voltage protocol to detect the maximally evoked tail current, we observed that exposure of exogenous cAMP did not have an immediate effect on the T‐type current, whereas long‐term exposure (> 24 hr) markedly increased the occurrence of high T‐type current in PMVECs. The increased T‐type current displayed virtually identical activation and inactivation properties as the original T‐type current, and correlated with an elevated mRNA level after 24 hr exposure to exogenous cAMP. Further, we revealed that 8CPT‐2Me‐cAMP, a selective cAMP‐regulated guanine nucleotide exchange factor (Epac) agonist, did not reproduce the effect of pCPT‐cAMP on T‐type current, while PKA inhibitor H89 and Rp‐cAMPS, a competitive antagonist of cAMP binding to PKA, prevented the action of pCPT‐cAMP. Together, these results support the idea that PKA‐dependent signaling pathways are involved in up‐regulation of Ca V 3.1 T‐type Ca 2+ channels in pulmonary microvascular endothelial cells. Supported by HL074116