Figure 2.

Direct visualization of mechanoelectric feedback in cardiomyocytes through IsoStretcher technology. (A) Thin polyvinyl-alcohol gel embedding of adult cardiomyocytes allows diffusion-limited accessibility to pharmacological manipulations as shown for application of a Ca²⁺ ionophore (5 μM ionomycin) to the external solution and visualization of a maximum Fluo-4 response after ~150 s (B). (C) Proof-of-concept recording demonstrating mechanoelectric feedback, i.e., the direct visualization of mechanical isotropic stretch (15% radial stretch) inducing early after- depolarization spontaneous Ca²⁺ transients (vertical arrows) upon sudden re-stretch from the relaxed state. Note that the dip in fluorescence reading during the brief relaxation is mostly due to the radial displacement of the respective cardiomyocytes out of the ROI, which however, is perfectly restored upon re-stretch.