Is PGI2 arrhythmogenic? investigations on ouabain induced arrhythmias in cats

The present study investigated the effect of PGI₂ on ouabain induced arrhythmias in cats. PGI₂ was infused at a dose of 1.0, 2.0 and 5.0 μg/kg·min. PGI₂ in a dose of 1.0 μg/kg·min was without any antiarrhythmic effect. Infusions of 2.0 and 5.0 μg/kg·min PGI₂ in 3 of 10 and 7 of 10 animals, respectively, converted the ouabain induced arrhythmias into a sinus rhythm. The duration of the antiarrhythmic effect after infusion of 2.0 μg/kg·min lasted about 21 min, whereas the higher dose (5.0 μg/kg·min) had a shorter effect (about 2 min). Under these conditions and doses the systolic blood pressure decreased between 35% and 39% and the diastolic blood pressure was reduced by about 50%. Thus PGI₂ showed, when used in the given dose range, an antiarrhythmic effect on ouabain induced arrhythmias in cats. The importance of dosage, methods and species is here discussed.