Ca2+ handling in isolated human atrial myocardium

被引:47
作者
Maier, LS
Barckhausen, P
Weisser, J
Aleksic, I
Baryalei, M
Pieske, B
机构
[1] Univ Gottingen, Zentrum Innere Med, Abt Kardiol & Pneumol, D-37075 Gottingen, Germany
[2] Univ Gottingen, Zentrum Chirurg, Abt Thorax Herz Gefasschirurg, D-37075 Gottingen, Germany
来源
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY | 2000年 / 279卷 / 03期
关键词
force-frequency relation; postrest behavior; human myocardium;
D O I
10.1152/ajpheart.2000.279.3.H952
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Physiologically, human atrial and ventricular myocardium are coupled by an identical beating rate and rhythm. However, contractile behavior in atrial myocardium may be different from that in ventricular myocardium, and little is known about intracellular Ca(2+) handling in human atrium under physiological conditions. We used rapid cooling contractures (RCCs) to assess sarcoplasmic reticulum (SR) Ca(2+) content and the photoprotein aequorin to assess intracellular Ca(2+) transients in atrial and ventricular muscle strips isolated from nonfailing human hearts. In atrial myocardium (n = 19), isometric twitch force frequency dependently (0.25-3 Hz) increased by 78 +/- 25% (at 3 Hz; P < 0.05). In parallel, aequorin light signals increased by 111 +/- 57% ( P < 0.05) and RCC amplitudes by 49 +/- 13% (P < 0.05). Similar results were obtained in ventricular myocardium (n = 13). SR Ca(2+) uptake (relative to Na(+)/Ca(2+) exchange) frequency dependently increased in atrial and ventricular myocardium (P < 0.05). With increasing rest intervals (1-240 s), atrial myocardium (n = 7) exhibited a parallel decrease in postrest twitch force (at 240 s by 68 +/- 5%, P < 0.05) and RCCs (by 49 +/- 10%, P < 0.05). In contrast, postrest twitch force and RCCs significantly increased in ventricular myocardium (n = 6). We conclude that in human atrial and ventricular myocardium the positive force-frequency relation results from increased SR Ca(2+) turnover. In contrast, rest intervals in atrial myocardium are associated with depressed contractility and intracellular Ca(2+) handling, which may be due to rest-dependent SR Ca(2+) loss (Ca(2+) leak) and subsequent Ca(2+) extrusion via Na(+)/Ca(2+) exchange. Therefore, the influence of rate and rhythm on mechanical performance is not uniform in atrial and ventricular myocardium.
引用
收藏
页码:H952 / H958
页数:7
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