Requirement of ryanodine receptors for pacemaker Ca2+ activity in ICC and HEK293 cells.
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.
Aoyama
Masahiro
M
Department of Physiological Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
Yamada
Aki
A
Wang
Jing
J
Ohya
Susumu
S
Furuzono
Shinji
S
Goto
Takayo
T
Hotta
Shingo
S
Ito
Yasushi
Y
Matsubara
Tatsuaki
T
Shimokata
Kaoru
K
Chen
S R Wayne
SR
Imaizumi
Yuji
Y
Nakayama
Shinsuke
S
D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D001896:Boron Compounds / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D007082:Ileum / Q000166:cytology* / Q000378:metabolism*; D007150:Immunohistochemistry; D007700:Kinetics; D047028:Macrocyclic Compounds; D051379:Mice; D008856:Microscopy, Fluorescence; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012433:Ryanodine / Q000378:metabolism / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism*; D016559:Tacrolimus / Q000494:pharmacology; D013748:Tetracaine / Q000494:pharmacology
D000779:Anesthetics, Local; D001896:Boron Compounds; D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D047028:Macrocyclic Compounds; D010080:Oxazoles; D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; C108644:xestospongin A; D013748:Tetracaine; D012433:Ryanodine; D002110:Caffeine; C109986:2-aminoethoxydiphenyl borate; D019009:Proto-Oncogene Proteins c-kit; D009543:Nifedipine; D002118:Calcium; D016257:Fura-2; D016559:Tacrolimus