The effect of voltage sensitive dye di-4-ANEPPS on the RT/RR coupling in rabbit isolated heart

Voltage sensitive dye (VSD) di-4-ANEPPS is ordinary used for optical measurement of action potential in experimental cardiology. In this work, the effect of the dye on the RT/RR coupling measured in electrograms (EG) recorded on rabbit isolated hearts was studied. The results were compared with the control experiments without VSD administration. The comparison was performed in preparation stage of the experiment that consisted of three phases: stabilization (S), VSD loading (L), and washout (W). The median and interquartile range (Q0.75-Q0.25) of the difference in RR, QT and RT/RR between the beginning and the end of the phases were computed and compared between the both groups. Δ(RT/RR), in S, L and W, was -0.095, 0.061; -0.093, 0.043; -0.027, 0.039 in di-4-ANEPPS-treated group and -0.127, 0.071; 0.006, 0.016; -0.001, 0.025 in control group. The significant difference (P<;0.01) was found between two groups in L phase. Additionally, there was the significant difference in ΔRR [ms] which was 120.9, 74.8 in di-4-ANEPPS-treated group and 6.94, 19.28 in control group in the same phase. The significant difference in Δ(RT/RR) between both groups shows a possible effect of di-4-ANEPPS on the RT/RR coupling which is mainly caused by the prolongation of RR interval during loading with the dye.