Comparison of voltage-sensitive dye di-4-ANNEPS effects in isolated hearts of rat, guinea pig, and rabbit

Voltage-sensitive dyes (VSDs) are used for recording of monophasic action potentials (MAPs) by optical method in excitable tissues. Their direct effects on the tissue are not completely elucidated. Previously we studied effects of VSD di-4-ANEPPS during staining and washout in Langendorff-perfused guinea pig and rabbit isolated hearts. However, most often used species in basic cardiology is rat. Therefore, we decided to compare the electrophysiological effects of VSD in isolated hearts of rabbit, guinea pig, and rat. Touch-less electrogram was recorded, the heart rate assessed and normalized. The type and incidence of arrhythmias were evaluated. Based on our results although the procedure of staining with the dye affects electrophysiological properties of the myocardium in all studied species - rat heart may be considered as the most suitable for electrophysiological studies using di-4-ANEPPS.