principle (part 3). ANIMALS AND METHODS

The hearts were paced at the right atrium via two platinum electrodes at 3 Hz, corresponding to their normal spontaneous basic cycle length of 343±21 ms (mean ± SEM, n=7). After 1 h of equilibration under standard conditions, the antiarrhythmic peptides were infused in increasing concentrations (0.1, 1, 10, 100, 300 nmol/L; 15 mins for each concentration). The infusion solution contained 0.05% bovine serum albumin (BSA). For control 0.05% BSA alone was infused for 15 mins before peptide application. In the control series without treatment, Tyrode’s solution was infused with 0.05% BSA at the same rate. Epicardial potential mapping was carried out in each experimental phase for a constant cycle length of at least 4 mins, making comparison of the activation patterns (of single heart beats) or their alterations possible. In addition, functional parameters – maximum systolic and end-diastolic left ventricular pressure, and coronary flow – were assessed continuously, as described previously.For evaluation of the mapping data, the activation time-points at each electrode were determined as t(dU/dtmin). Next, the repolarization timepoints were determined as t(dU/dtmax) during the T wave, as described previously . From these data for each electrode an activation recovery interval (ARI), corresponding to the epicardial potential duration, was calculated. The distribution of ARI was analyzed for each area of the heart (ie, front, left, right or back wall) by calculating the standard deviation of ARI at 64 electrodes and expressed as ARI dispersion. For better description, the percentage of the 256 ARI values, which were in the range of ±5 ms around the mean ARI, was calculated. In addition, the ST segments of the 256 electrocardiograms were analyzed. All deviations from the isoelectrical level at the timepoint 50% of mean ARI were summed and the total ST deviation of 256 leads was calculated in arbitrary units. Moreover, the total activation time in every heart region was determined as the latency between the activation timepoints of the first and the last electrode being activated in a given heart region. This is a great opportunity for you to start saving some money instead of spending it all: you now have a perfectly reliable pharmacy you can buy ortho tri-cyclen buy here from any time there is such a need and without being worried about the safety of your private information.

Category: Cardiology / Tags: Antiarrhythmic drugs, Antiarrhythmic peptides, Cardiac arrhythmia, Cellular coupling, Gap junction

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