頁籤選單縮合
題 名 | Differential Electromechanical Effects of Cyclopiazonic Acid on Conducting and Working Tissues of the Canine Heart |
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作 者 | Chen, Kwan-yu; Lin, Chun-lun; Shih, Tzu-cheng; Lin, Cheng-i; | 書刊名 | 醫學工程 |
卷 期 | 11:3 民88.06 |
頁 次 | 頁105-112 |
分類號 | 415.12 |
關鍵詞 | Tissue engineering; SR CA[fec7]-ATPase inhibitor; Action potential; Contraction electrical pacing; Postrest potentiation; |
語 文 | 英文(English) |
英文摘要 | Objectives: The present experiments study electromechanical properties and pharmacological response to an inhibitor of sarcoplasmic reticulum Ca ���� -ATPase (SERCA2a), cyclopiazonic acid (CPA), in isolated dog Purkinje fibers and ventricular trabeculae. Methods and Results: Strands of Purkinje fibers and trabecular muscles were removed from endocardial surface of ventricles of 12 mongrel dogs. Transmembrane action potential was recorded by means of conventional microelectrode techniques and twitch force by means of a force-displacement transducer. The preparations were driven electrically at a basic rate of 1 Hz. Electrical stimulation was interrupted for intervals ranging from 5, 10, 20, 40 to 60 s and post-rest potentiation of contraction (PRPC) was measured in the absence and presence of CPA. The results show that both Purkinje fibers and ventricular trabeculae undergo PRPC but Purkinje fibers had a much shorter half time for maximum potentiation (3 s) than that of ventricular muscles (13 s). In ventricular muscle trabeculae, CPA (3-10 μ M) decreased the PRPC without consistent change in the steady-state contraction. In Purkinje fibers, CPA significantly decreased steady-state contraction but increased PRPC. In addition, CPA depressed action potential plateau, induced oscillations of diastolic potential during rest interval and facilitated the onset of spontaneous activity. Conclusions: The increased PRPC and changes in membrane potential by CPA suggest that sarcolemmal Na �� -Ca ���� exchanger may play a greater role in the regulation of cytosolic [Ca ���� ] in Purkinje fiber than in ventricular muscle. It is indicated that CPA, through actions on SERCA2a and Na �� -Ca ���� exchanger, causes excessive accumulation of cytosolic Ca ���� during rest interval leading to an increased PRPC. |
本系統中英文摘要資訊取自各篇刊載內容。