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  • Requirement of ryanodine receptors for pacemaker Ca2+ activity in ICC and HEK293 cells.

Requirement of ryanodine receptors for pacemaker Ca2+ activity in ICC and HEK293 cells.

Journal of cell science (2004-06-01)
Masahiro Aoyama, Aki Yamada, Jing Wang, Susumu Ohya, Shinji Furuzono, Takayo Goto, Shingo Hotta, Yasushi Ito, Tatsuaki Matsubara, Kaoru Shimokata, S R Wayne Chen, Yuji Imaizumi, Shinsuke Nakayama
ABSTRACT

Intracellular Ca(2+) ([Ca(2+)](i)) oscillations seen in interstitial cells of Cajal (ICCs) are considered to be the primary pacemaker activity in the gut. Here, we show evidence that periodic Ca(2+) release from intracellular Ca(2+) stores produces [Ca(2+)](i) oscillations in ICCs, using cell cluster preparations isolated from mouse ileum. The pacemaker [Ca(2+)](i) oscillations in ICCs are preserved in the presence of dihydropyridine Ca(2+) antagonists, which suppress Ca(2+) activity in smooth muscle cells. However, applications of drugs affecting either ryanodine receptors or inositol 1,4,5-trisphosphate receptors terminated [Ca(2+)](i) oscillations at relatively low concentrations. RT-PCR analyses revealed a predominant expression of type 3 RyR (RyR3) in isolated c-Kit-immunopositive cells (ICCs). Furthermore, we demonstrate that pacemaker-like global [Ca(2+)](i) oscillation activity is endowed by introducing RyR3 into HEK293 cells, which originally express only IP(3)Rs. The reconstituted [Ca(2+)](i) oscillations in HEK293 cells possess essentially the same pharmacological characteristics as seen in ICCs. The results support the functional role of RyR3 in ICCs.

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Sigma-Aldrich
Monoclonal Anti-Ryanodine Receptor antibody produced in mouse, clone 34C, ascites fluid