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Reverse mode sodium‐calcium exchange (NCXrev) facilitated by co‐localization of the exchanger with TRPC channels contributes to Ca2+ influx and ER Ca2+ store refilling during agonist stimulation of endothelial cells
Author(s) -
Liao ChiuHsiang,
Breemen Cornelis,
Braun Andrew P.,
Cole William C.
Publication year - 2010
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.24.1_supplement.819.3
Subject(s) - trpc , chemistry , transient receptor potential channel , stimulation , trpc5 , agonist , medicine , microbiology and biotechnology , endocrinology , biophysics , receptor , biochemistry , biology
The role of NCX as a mechanism for Ca 2+ entry is receiving increased attention. NCX and TRPC channels were shown to co‐localize, facilitating NCX rev mediated Ca 2+ influx in response to TRPC activation in over‐expression studies (Rosker C et al., JBC 279:13696 (2004)). Here, we employed patch clamp technique, Ca 2+ fluorimetry and co‐immunoprecipitation to determine if: 1) NCX rev contributes to Ca 2+ influx in response to agonist stimulation, and 2) TRPC and NCX are co‐localized in cultured endothelial cells (EA.Hy926). Stimulation with histamine increased steady‐state inward and outward current between −70 and +70 mV in K + ‐free solution; KB‐R7943 inhibition of NCX selectively suppressed outward current, but SKF96365 inhibition of TRPC reduced both inward and outward currents. Histamine caused an increase in Fura‐2 cytosolic Ca 2+ fluorescence and a reduction in ER Ca 2+ D1ER fluorescence. SKF96365 and KB‐R7943 suppressed the increase in cytosolic [Ca 2+ ] and enhanced the depletion of ER Ca 2+ stores induced by histamine. Significantly, TRPC1, TRPC4 and caveolin‐1 immunoreactive proteins were detected in anti‐NCX1 immunoprecipitates of endothelial cell lysates. These findings suggest that co‐localization of NCX and TRPC channels in a signaling complex in endothelial cells may facilitate Ca 2+ influx and ER Ca 2+ store refilling via NCX rev during agonist stimulation. (funded by CIHR MOP‐13505, NSERC and AHFMR).