2.3. Attachment of single cardiomyocyte

Cardiomyocytes were glued to 35 μm glass needles that were attached to the cantilever of the force transducer and to the piezo-translator (Figure 1C). The needles were between 0.5 and 1.5 mm long, and were sufficiently stiff to prevent bending during the contractions. The gluing procedure is similar to the method described by Prosser et al.¹⁸ The tips were coated with an aluminium silicate suspension (Ionoptix pre-coat). The pre-coat was air-dried after which they were dipped in MyoTak (Ionoptix). In a well-attached cell, we could do force measurements for up to an hour in a temperature-controlled chamber (see Supplementary material online, FigureS1) at 37°C without significant run-down of the preparation.