Involvement of ryanodine receptors in pacemaker Ca2+ oscillation in murine gastric ICC |
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Authors: | Liu Hong-Nian Ohya Susumu Wang Jing Imaizumi Yuji Nakayama Shinsuke |
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Institution: | Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan. |
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Abstract: | Using a cell cluster preparation from the stomach smooth muscle tissue of mice, we measured intracellular Ca(2+) oscillations in interstitial cells of Cajal (ICCs) in the presence of nifedipine. Pacemaker Ca(2+)](i) activity in ICCs was significantly suppressed by caffeine application and restored after washout. Application of either ryanodine or FK-506 terminated the pacemaker Ca(2+)](i) activity irreversibly. Immunostaining of smooth muscle tissue showed that c-Kit-immunopositive cells (that form network-like structure cells in the myenteric plexus, equivalent to ICCs) clearly express ryanodine receptors (RyR). RT-PCR revealed that ICCs (identified with c-Kit-immunoreactivity) predominantly express type 3 RyR (RyR3). Furthermore, the FK-binding proteins 12 and 12.6, both of which would interact with RyR3, were detected. In conclusion, we provide first evidence for the essential contribution of RyR to generating pacemaker activity in gastric motility. Similar mechanisms might account for spontaneous rhythmicity seen in smooth muscle tissues distributed in the autonomic nervous system. |
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Keywords: | Stomach Pacemaker Calcium oscillations c-Kit-immunopositive cells Interstitial cells of Cajal Ryanodine receptors FK506-binding proteins Caffeine |
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