The effect of dietary fatty acids on cellular calcium handling mechanisms in cardiac muscle

发达国家的一个主要健康问题是心血管疾病，其表现为高血压、中风、心脏病发作和心律失常或心律失常。西方饮食，即。高动物脂肪或饱和脂肪可能是罪魁祸首。人类流行病学研究表明，食用高饱和脂肪的饮食与心律失常的倾向有关，而多不饱和脂肪酸（PUFA）含量高的饮食可以防止冠心病和心律失常。这些影响的机制尚未完全了解。心脏的收缩取决于单个肌肉细胞内钙的变化。钙在细胞中的处理方式异常会导致收缩异常和某些类型的心律失常。在过去的5到10年里，技术的发展使我们能够在微观水平上研究活心脏细胞中钙的变化。可以用荧光染料填充单个活细胞，该荧光染料根据周围的钙浓度改变其荧光的大小或波长。用激光扫描共聚焦显微镜检查充满这些染料的细胞，其中非常紧密聚焦的激光束激发染料，并且通过计算机控制的图像分析系统收集所得荧光。通过这种方式，我们可以测量细胞内的钙浓度，空间分辨率约为1-1000毫米，时间分辨率约为1-100秒。使用这些技术，我们发现，用PUFA或饱和脂肪补充大鼠的饮食，会使钙在心脏细胞中的储存和释放方式发生巨大变化。膳食脂肪的这种作用以前没有报道过，它可能代表了这些物质如何防止许多心律失常的重要线索。

A major health problem in the developed countries is cardiovascular disease, which is manifest as high blood pressure, stroke, heart attack and abnormalities of heart rhythm, or cardiac arrhythmias. A western diet, ie. one high in animal fat, or saturated fats, may be to blame. Human epidemiological studies have shown that consumption of a diet high in saturated fats is correlated with a propensity to arrhythmias while a diet high in polyunsaturated fatty acids (PUFAs) can confer protection from coronary heart disease and cardiac arrhythmias. The mechanisms underlying these effects are not fully understood. The contraction of the heart depends on changes in calcium inside the individual muscle cells. Abnormalities of the way calcium is handled in the cells leads to abnormalities of contraction and to a certain types of arrhythmia. Over the last 5 to 10 years, technological developments have enabled us to examine changes in calcium in living heart cells at microscopic level. It is possible to fill individual living cells with a fluorescent dye which changes either the magnitude or the wavelength of its fluorescence according to the ambient calcium concentration. Cells filled with these dyes are examined with a laser scanning confocal microscope, in which a very tightly focussed laser beam excites the dye and the resulting fluorescence is gathered by a computer controlled image analysis system. In this way we can measure the calcium concentration within the cells with a spatial resolution of about 1-1000 of a millimetre, and a time resolution of about 1-100 of a second. Using these techniques, we have found that supplementing the diet of rats with either PUFAs or saturated fats produces a dramatic change in the way that calcium is stored and released in their heart cells. This effect of dietary fats has not been reported before, and it may represent an important clue as to how these substances protect against many cardiac arrhythmias.