Open AccessLocalized Ca 2+ uncaging induces Ca 2+ release through IP 3 R in smooth muscle
Author(s) -
WANG Min,
CHEN Zheng,
XING Yan,
ZHANG Xu,
DONG Xianzhi,
JI Guangju
Publication year - 2006
Publication title -
acta pharmacologica sinica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.514
H-Index - 90
eISSN - 1745-7254
pISSN - 1671-4083
DOI - 10.1111/j.1745-7254.2006.00389.x
Subject(s) - ryanodine receptor , biophysics , chemistry , egta , inositol , flash photolysis , confocal , phospholipase c , calcium , intracellular , receptor , biochemistry , biology , kinetics , physics , geometry , mathematics , organic chemistry , quantum mechanics , reaction rate constant
Aim: Our previous study indicated that there are two types of Ca 2+ release events seen in intact mouse bladder tissue. In this study our aim is to investigate the mechanism that underlies the phenomena of Ca 2+ release in smooth muscle. Methods : Single cells were isolated and tissue segments were prepared by cutting the detrusor into 0.1 cm×0.5 cm strips running along the axis from the neck to the fundus. Single cells and intact tissue strips were co‐loaded with the Ca 2+ indicator and caged Ca 2+ by incubation with 10 μmol/L Fluo‐4 AM and DMNP‐EDTA‐AM. Fluo‐4 AM fluorescence was detected by laser scanning confocal microscopy, and local uncaging of DMNP‐EGTA was achieved by brief exposure to the output of a diode‐pumped, Ti:sapphire laser tuned to 730 nm. Results : Local uncaging of caged Ca 2+ was able to trigger Ca 2+ release events in both single cells and tissue strips from mouse bladder. The Ca 2+ release events could not be blocked by ryanodine alone, but the property of the Ca 2+ release was markedly altered. Surprisingly, in the presence of ryanodine, Xestospongin C completely inhibited the Ca 2+ release events both in single cell and tissue experiments. Conclusion: (1) Two photon flash photolysis (TPFP) triggers Ca 2+ induced Ca 2+ release. This process involves release through type 2 ryanodine receptor channels; (2) TPFP results in the release of Ca 2+ through inositol 1,4,5‐trisphosphate receptors in the absence of phospholipase C activation.