ABNORMAL CAI2+ HANDLING IS THE PRIMARY CAUSE OF MECHANICAL ALTERNANS - STUDY IN FERRET VENTRICULAR MUSCLES
ABNORMAL CAI2+ HANDLING IS THE PRIMARY CAUSE OF MECHANICAL ALTERNANS - STUDY IN FERRET VENTRICULAR MUSCLES
复制标题
DOI：
10.1152/ajpheart.1991.261.6.h1746
复制
发表时间：
1991-12-01
影响因子：
--
通讯作者：
MORGAN, JP
中科院分区：
文献类型：
--
作者：
KIHARA, Y;MORGAN, JP
我们测试了心脏的机械交替是由于细胞内钙（Ca（i）2+）水平的改变的假设。从雄性雪貂的右心室分离八个乳头肌，并用水母发光蛋白化学负载以记录胞质Ca（i）2+。为了产生稳态机械交替，在22 ℃下用含有低钙浓度（0.25 mM）的生理盐溶液灌注制剂，并在卡巴胆碱和普萘洛尔存在下以0.5-1.0 Hz刺激。同时记录水母发光蛋白信号（Ca（i）2+）和等长收缩。在每一块肌肉中，强搏动（具有较高峰值张力的搏动）与较弱搏动更大的Ca 2+瞬变相关。在强搏动和弱搏动期间，峰值Ca（i）2+和峰值张力之间的关系也被短期频率响应类似地修改。另一方面，等长收缩和Ca ~（2+）瞬变在强搏动和弱搏动期间的时间过程是重叠的。这些数据表明，机械交替是由可用于激活肌丝的Ca（i）2+的交替变化引起的。延长肌浆网再循环Ca 2+的时间，即，肌浆网中钙泵的摄取功能降低，伴随着钙从摄取区室向释放区室的缓慢转运，被认为是机械交替期间异常Ca（i）2+处理的原因。
We tested the hypothesis that mechanical alternans of the heart is due to alterations in intracellular calcium (Ca(i)2+) levels. Eight papillary muscles were isolated from the right ventricles of male ferrets and were chemically loaded with aequorin to record cytoplasmic Ca(i)2+. To produce a steady-state mechanical alternans, the preparations were perfused with a physiological salt solution containing a low calcium concentration (0.25 mM), at 22-degrees-C, and stimulated at 0.5-1.0 Hz in the presence of carbachol and propranolol. The aequorin signal (Ca(i)2+) and isometric contraction were simultaneously recorded. In each muscle, the strong beats (beats with higher peak tension) were associated with larger Ca2+ transients than the weak beats. The relationships between peak Ca(i)2+ and peak tension, both during strong and weak beats, were similarly modified by short-term frequency responses. On the other hand, the time courses of the isometric contractions and Ca2+ transients during strong beats and weak beats were superimposable. These data indicate that mechanical alternans is caused by an alternate change of Ca(i)2+ available for activation of the myofilaments. Prolongation of the time for recycling Ca2+ by the sarcoplasmic reticulum, i.e., a depressed uptake function of the Ca2+ pump with concomitant slow transportation of Ca2+ from the uptake compartment to the release compartment in the sarcoplasmic reticulum, is suggested as a cause of the abnormal Ca(i)2+ handling during mechanical alternans.