| Project/Area Number |
08457205
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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 |
Circulatory organs internal medicine
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| Research Institution | Research Institute of Environmental Medicine, Nagoya University. |
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Principal Investigator |
KODAMA Itsuo Nagoya Univ., Res.Inst.of Environ.Med., Professor, 環境医学研究所, 教授 (30124720)
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| Co-Investigator(Kenkyū-buntansha) |
HONJO Haruo Nagoya Univ., Res.Inst.of Environ.Med., Research Associate, 環境医学研究所, 助教授 (70262912)
TAKAGISHI Yoshiko Nagoya Univ., Res.Inst.of Environ.Med., Associate Professor, 環境医学研究所, 助手 (50024659)
TOYAMA Junji Nagoya Univ., Res.Inst.of Environ.Med., Professor, 環境医学研究所, 教授 (20023658)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1997: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1996: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | heart / sinoatrial node / confocal microscopy / immunohistochemistry / connexin / gap junction / K+ channel / ギャップジャンクション / actin filament / phalloidine / connexin43 |
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| Research Abstract |
Although the electrophysiological properties of sinoatrial (SA) node pacemaker cells have been well characterized, only limited information is available about the molecular mechanisms underlying the distinct electrical properties. In the present study, the expression and distribution of gap junctional proteins and K+ channels have been studied by immunofluorescence techniques.
1.Expression of connexins in the SA node.
The rabbit SA node was stained with subtype-specific anti-connexin antibodies and was analyzed by confocal microscopy. The following results were obtained : 1)The SA node cells did not express connexin43 but did express connexin45.2)Connexin40 also appeared to be expressed by the SA node cells. 3)There were regions of tissue preparation, in particular, the endocardial side, in which the cells expressed both connexin45 and 43. The expression of different types of connexins in the SA node in addition to scarce formation of small gap junctions might be involved in the reduced intercellular coupling conductance between SA node cells.
2.Expression and localization of the Kv1.5 channel in the SA node.
We have previously reported that 4-AP has marked effects on the electrical activity of the SA node. In this study, the distribution of Kv1.5 channel, one of the 4-AP sensitive cloned K+ channels, has been studied in and around the guinea pig SA node. Kv1.5 was abundantly expressed in the SA node as well as the atrial muscle, although the subcellular distribution was different in the two tissues. In the atrial muscle, Kv1.5 channel was localized predominantly at the intercalated disk regions in close apposition with connexin43, whereas in the SA node Kv1.5 was more dispersed throughout the cell membrane. The role of the Kv1.5 channel in the SA node has not well established, but it may partly underlie the marked effects of 4-AP on the SA node.
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