Optogenetic quantification of cardiac excitability and electrical coupling in intact hearts to explain cardiac arrhythmia initiation.

ABSTRACT: Increased cardiac excitability and reduced electrical coupling promote cardiac arrhythmia and can be quantified by input resistance (R_m), pacing threshold (I_thr), and cardiac space constant (λ). However, their measurement in the heart was not feasible because the required homogenous current injection cannot be performed with electrical stimulation. We overcame this problem by optogenetic current injection into all illuminated cardiomyocytes of mouse hearts in different action potential phases. Precisely triggered and patterned illumination enabled measuring R_m and λ, which both were smallest at diastole. Pharmacological and depolarization-induced reduction of inwardly rectifying K⁺ currents (I_K1), gap juncti

SUBMITTER: Langen JS 

PROVIDER: S-EPMC11870084 | biostudies-literature | 2025 Feb

REPOSITORIES: biostudies-literature