The Journal of Physiological Sciences | |
Use of the Ca-Shortening Curve to Estimate the Myofilament Responsiveness to Ca2+ in Tetanized Rat Ventricular Myocytes | |
Makoto Kawai3  Masato Konishi1  Yoichiro Kusakari2  Kenichi Hongo3  Satoshi Kurihara2  | |
[1] Department of Physiology (I), Tokyo Medical University;Department of Physiology (II), The Jikei University School of Medicine;Division of Cardiology, The Jikei University School of Medicine | |
关键词: calcium (cellular); contractile function; inotropic agents; myocytes; second messengers; | |
DOI : 10.2170/physiolsci.RP003706 | |
学科分类:生理学 | |
来源: Springer | |
【 摘 要 】
References(29)Cited-By(1)We previously estimated the myofilament responsiveness to Ca2+ in isolated intact ventricular myocytes, using the steady-state relationship between cytosolic Ca2+ concentration ([Ca2+]i) and cell-shortening during tetanus (Ca-L trajectory). This method was useful and easy; however, it could not be used for a high dose of Ca sensitizer because the instantaneous plots after the application of Ca sensitizer did not make a fixed point of shortening (we used 5% shortening). Therefore we must produce another method to investigate Ca2+ responsiveness. For an estimation of a wider range of the Ca-L trajectory, we fitted the Ca-L trajectory data with the Hill equation to construct the Ca-shortening curve. To fit this curve, we measured the maximal shortening, which was on average 31.6%. The value of [Ca2+]i to produce the half-maximal shortening (Ca50) was dose-dependently decreased by EMD57033 (sensitization). Either isoproterenol or 3-isobutyl-1-methylxanthine increased Ca50 (desensitization) with a concomitant increase in intracellular c-AMP. EMD57439, a selective PDE-III inhibitor, did not significantly increase the c-AMP concentration and produced little change in Ca50. These results are in agreement with previous reports with skinned or intact multicellular preparations. The Ca-shortening curve constructed in intact cardiac myocytes can be used to estimate the myofibrillar responsiveness to Ca2+ in a wide range of [Ca2+]i.
【 授权许可】
Unknown
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