Ca²⁺ handling within cardiac myocytes underpins coordinated contractile function within the beating heart. This protocol enables high spatial and temporal Ca²⁺ imaging of ex vivo multicellular myocardial strips. The endocardial surface is retained, and strips of 150–300-µm thickness are dissected, loaded with Ca²⁺ indicators and mounted within 1.5 h. A list of the equipment and reagents used and the key methodological aspects allowing the use of this technique on strips from any chamber of the mammalian heart are described. We have successfully used this protocol on human, pig and rat biopsy samples. On use of this protocol with intact endocardial endothelium, we demonstrated that the myocytes develop asynchronous spontaneous Ca²⁺ events, which can be ablated by electrically evoked Ca²⁺ transients, and subsequently redevelop spontaneously after cessation of stimulation. This protocol thus offers a rapid and reliable method for studying the Ca²⁺ signaling underpinning cardiomyocyte contraction, in both healthy and diseased tissue.

心肌细胞内的Ca ^{2+处理支持跳动的心脏内协调的收缩功能。}该协议能够对体外多细胞心肌条进行高空间和时间 Ca ^2+成像。保留心内膜表面，解剖厚度为 150–300 µm 的条带，装入 Ca ²⁺指示剂并在 1.5 小时内安装。描述了使用的设备和试剂清单以及允许在哺乳动物心脏任何腔室的条带上使用该技术的关键方法学方面。我们已经成功地将这个协议用于人类、猪和大鼠的活检样本。在使用该方案与完整的心内膜内皮细胞时，我们证明了肌细胞发展出异步自发 Ca ²⁺事件，可以通过电诱发的 Ca ²⁺瞬变消融，随后在停止刺激后自发地重新发展。因此，该协议提供了一种快速可靠的方法，用于研究健康和患病组织中支持心肌细胞收缩的 Ca ^2+信号。