Abstract
The Ca2+ release activity of inositol 1, 4, 5-trisphosphate receptor (InsP3R) is biphasically dependent on the cytoplasmic Ca2+ concentration: activation near 100 nM and inhibition around 1 μM. We have found that the cytoplasmic Ca2+ concentration is not simply a modulator of InsP3R but is an indispensable factor for channel activation. The Ca2+ requirement of InsP3R places the Ca2+ release channel within a Ca2+-mediated positive feedback loop, which has been demonstrated with caged InsP3 and Ca2+. The positive feedback mechanism seems to be the important basis for the generation of Ca2+ wave in various cell types including smooth muscle cells. To further clarify the role of Ca2+ stores in the smooth muscle function, we measured the Ca2+ concentration in individual smooth muscle cells in isolated vascular tissues stimulated with perivascular sympathetic nerves using a confocal microscope. We observed in these cells Ca2+ waves/oscillations due to Ca2+ release from the stores. These results show that the Ca2+ requirement of InsP3 receptor plays an important role in the regulation of vascular contraction. They also throw new light on both pharmacological and pathophysiological studies of vascular tone.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
