Interaction of serotonin and deslanoside on cardiac rhythm in the cat.

The present study was performed to determine whether increases in the tissue content of serotonin creatinine SO4 in the periphery would influence the arrhythmogenic effect of deslanoside. This was accomplished by infusing serotonin into anesthetized cats exposed to a subarrhythmic dose of deslanoside, determining doses of deslanoside required to produce ventricular tachycardia and ventricular fibrillation, and determining ventricular pacemaker rate (obtained during vagal-induced sinus node suppression). It was found that animals receiving serotonin creatinine SO4 plus deslanoside exhibited a greater increase in ventricular rate during sinus node suppression than with 5-HT infusion alone. No corresponding increase in ventricular pacemaker rate during sinus node suppression was observed with creatinine SO4 plus deslanoside. In addition, the dose of deslanoside to produce ventricular fibrillation in these animals was significantly correlated with the increase in ventricular pacemaker rate seen during th 5-HT infusion in the presence of deslanoside. Studies were also performed to determine whether the arrhythmogenic interaction of serotonin with deslanoside was associated with alterations in either cardiac tissue, blood or plasma levels of serotonin and 5-hydroxyindoleacetic acid. The data revealed a significant correlation between serotonin content in the left ventricle and the dose of deslanoside required to produce ventricular fibrillation. These results suggest that exogenous serotonin interacts with deslanoside to enhance the arrhythmogenic action of deslanoside.