CA2+ HANDLING AND MYOFIBRILLAR CA2+ SENSITIVITY IN FERRET CARDIAC MYOCYTES WITH PRESSURE-OVERLOAD HYPERTROPHY

被引:23
作者
WANG, JX
FLEMAL, K
QIU, ZH
ABLIN, L
GROSSMAN, W
MORGAN, JP
机构
[1] HARVARD UNIV,BETH ISRAEL HOSP,THORNDIKE LAB,DEPT MED,DIV CARDIOVASC,BOSTON,MA 02215
[2] HARVARD UNIV,SCH MED,BOSTON,MA 02215
来源
AMERICAN JOURNAL OF PHYSIOLOGY | 1994年 / 267卷 / 03期
关键词
AEQUORIN; CALCIUM INDICATORS; DIASTOLIC RELAXATION; EXCITATION-CONTRACTION COUPLING;
D O I
10.1152/ajpheart.1994.267.3.H918
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Experiments were performed in aequorin-loaded left ventricular myocytes isolated from hypertrophied hearts and age-matched controls. Five to six months after postvalvular aortic banding, left ventricular hypertrophy was present, as indicated by a 97% (P < 0.001) increase in the left ventricular weight-to-body weight ratio and a 24% (P < 0.001) increase in cell width. In comparison with controls, the hypertrophied myocytes demonstrated that 1) contraction duration was prolonged by 37% (P < 0.001) and was associated with a 44% (P < 0.001) prolongation of the intracellular Ca2+ transient; 2) peak systolic shortening was decreased by 31% (P < 0.001) and was associated with a 21% (P < 0.001) decrease in peak systolic intracellular Ca2+ concentration; 3) both the peak systolic intracellular Ca2+ concentration-to-peak shortening relationship and the intracellular Ca2+ concentration-to-cell shortening relationship at the time of the peak twitch were shifted downward, suggesting a decrease in myofilament Ca2+ responsiveness; and 4) isoproterenol (5 x 10(-8) M) produced equal increases in the peak systolic intracellular Ca2+ of control and hypertrophied myocytes (88 vs. 90%; P > 0.05) in contrast to much smaller increases in the peak cell shortening (170 vs. 73%; P < 0.02) of the hypertrophied myocytes, suggesting a decrease in myofilament Ca2+ responsiveness. These data demonstrate that the hypertrophy-related abnormalities in intracellular Ca2+ handling and mechanical function, previously reported in aequorin-loaded multicellular muscle preparations, are present in isolated myocytes, arguing against changes in the interstitium as essential causative factors.
引用
收藏
页码:H918 / H924
页数:7
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