Objectives: 

It has been reported that IKATP blockade using glibenclamide produces several antiarrhythmic effects in ischemic myocardium, like a heterogeneity decrease and other effects. Nevertheless, the possible effects in normoxic conditions on refractoriness dispersion (as a heterogeneity index) of the above mentioned blocker is less known. The aim of this study is to test whether glibenclamide modifies myocardial electrophysiological heterogeneity, by means of ventricular refractoriness dispersion analysis, in isolated and perfused (well-oxygenated) heart, and not submitted to ischemic conditions.

Materials: 

Twenty-one NZW rabbits were anesthetized (ketamine, 10 mg/kg i.v.), euthanized and the hearts excised, isolated and perfused in a Langendorff system. A pacing electrode and a plaque with 256 recording electrodes were positioned on the left ventricle. VF was induced at increasing frequencies. It was determined the functional refractory period during the VF (FRPVF) in each unipolar electrode (as the 5th percentile of the VF cycle length histogram), and the coefficient of variation of this parameter (CVFRP): FRPVF standard deviation/FRPVF mean. Two groups were made: control (n = 10) and treated (n = 11) with the inhibitor of IKATP, glibenclamide (10 mM). Determinations were performed 5 minutes after VF triggering. An unpaired student t test was applied to compare CVFRP between groups. Significance when p < 0,05.

Results: 

Although there were no differences between control and treated group (18,5 ± 1,8 %; n = 10 vs. 15,9 ± 4,1 %; n = 11) a tendency (p = 0,08) to CVFRP decrease by glibenclamide was observed.

Conclusions: 

Other effects than IKATP blockade by glibenclamide could also play a role in the antiarrhythmic protecting effects of this IKATP blocker.

Acknowledgement: 

This research was supported by a grant (DEP2010-22318-C02-01) from Ministerio de Ciencia e Innovación (Spain) and by a grant (PROMETEO2010/093) from Generalitat Valenciana (Spain).