Voltage sensitive optical mapping used to observe effects of late Na and rapidly activating delayed rectifier K currents on the right and left ventricular electrophysiological heterogeneity / 西安交通大学学报(医学版)

ABSTRACT

ABSTRACTObjective To observe the effects of late Na current (INa‐L ) and rapidly activating delayed rectifier K current (IKr ) on ventricular heterogeneity and frequency dependency by using high resolution voltage sensitive optical mapping technology .Methods The model of 12 isolated hearts was constructed in rabbits . Voltage sensitive dye Di‐4‐ANEPPS were perfused into the isolated hearts by Langendorff method .LED source with the wave length of 532 nm was used to record APD80 and APD50 of the left and right ventricles .Experimental groups were divided into 3 groups by perfusion drugs dofetillide (30 nmol/L) ,dofetillide+ATX‐Ⅱ(1 nmol/L) ,and dofetillide +ATX‐Ⅱ +mexiletine (10μmol/L) .The subjects were intervened by the above drugs in order ,and they were self‐compared before dosing .After each drug administration ,the hearts were stimulated respectively with the BCL of 2 000 ms ,1 000 ms ,500 ms ,and 300 ms .Then we observed the changes of APD80 and APD50 in the left and right ventricles before and after the interventions .Results ① In the control group ,APD80 and APD50 of the right ventricle were longer than those of the left ventricle in response to different stimulation , and the differences increased with the decrease of stimulating frequency .② When BCL was 1000 ms ,APD80 and APD50 of the left and right ventricles were prolonged respectively after administration of dofetillide , but the differences in APD80 and APD50 were insignificant between the left and right ventricles (P>0 .05) .ΔAPD80 of the two ventricles increased significantly with the decrease of stimulating frequency . ③ After administration of ATX‐Ⅱ , when BCL was 1000 ms ,APD80 and APD50 of the left and right ventricles increased significantly compared with those in the control group and dofetillide intervention group (P0 .05) .The increase of ΔAPD80 of the two ventricles became milder when the stimulating frequency decreased . Conclusion ① IKr blocked by dofetillide did not affect the heterogeneity between the two ventricles , which showed reverse‐frequency dependence . ② In the context of blocking IKr , ATX‐Ⅱ increased the heterogeneity between the left and right ventricles and enhanced the reverse‐frequency dependence .In contrast ,mexiletine ,the blocker of INa‐L ,decreased the heterogeneity between the two ventricles and reverse‐frequency dependence .