Species Difference in the Contribution of T-Type Calcium Current to Cardiac Pacemaking as Revealed by R(−)-Efonidipine
The contribution of the T-type Ca2+ current to cardiac pacemaking was examined in isolated right atrial tissue from the mouse, guinea pig, and rabbit using a specific blocker, R(−)-efonidipine. At 10−6 M, R(-)-efonidipine produced negative chronotropy, which was prominent in the mouse and small but...
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| Main Authors: | , , , , , , , |
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| Format: | Book |
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Elsevier,
2008-01-01T00:00:00Z.
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| Summary: | The contribution of the T-type Ca2+ current to cardiac pacemaking was examined in isolated right atrial tissue from the mouse, guinea pig, and rabbit using a specific blocker, R(−)-efonidipine. At 10−6 M, R(-)-efonidipine produced negative chronotropy, which was prominent in the mouse and small but significant in the guinea pig. No effect was observed in the rabbit. Microelectrode recordings revealed that R(-)-efonidipine significantly prolongs the pacemaker (phase 4) depolarization of the sinoatrial-node action potential in the mouse and guinea pig. These results provide the first pharmacological evidence that the contribution of T-type Ca2+ current to cardiac pacemaking differs among experimental animal species. Keywords:: R(-)-efonidipine, T-type Ca2+ current, cardiac pacemaking |
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| Item Description: | 1347-8613 10.1254/jphs.SC0070405 |