1996 Fiscal Year Final Research Report Summary
A new sastained inward current in the cardiac pacemaker cells.
| Project/Area Number |
08457010
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
NOMA Akinori Kyoto Univ.Faculty of Medicine, Dept.of Physiology Prof., 医学研究科, 教授 (00132738)
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| Co-Investigator(Kenkyū-buntansha) |
MITSUIYE Tamotsu Kyoto Univ.Faculty of Medicine Dept of Physiology Associate Prof., 医学研究科, 助教授 (40174065)
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| Project Period (FY) |
1996
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| Keywords | Cardiac pacemaker / Sino atrial node / Spontaneous Action Potential / Sustained Inward Current |
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| Research Abstract |
The ion selectivity of the sustained inward current was investigated. The whole cell recording from rabbit SA node cells showed activation of the sustained inward current at potentials positive to -70mV,while the activation of the L-type Ca^<2+> current was observed at potentials positive to -40mV.This sustained inward remained intact when the external Ca^<2+> concentration was lowered to 0.1mM,at which the L-type Ca^<2+> current was totally suppressed. On the other hand depletion of the external Na^+ removed the sustained inward current, while the L-type Ca^<2+> current remained at potentials positive to -40mV.The amplitude of the sustained inward current was varied by replacing the external Na^+ with various cations, Na^+>Li^+>K^+=Cs^+.
The sustained iward current was also observed in guinea-pig and rat SA node cells. The rabbit AV node cells, showing spontaneous action potentials, also possessed the sustained inward current. These findings stongly suggested that the sustained inward current play an essential role in driving the diastolic depolarization.
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