Experimental study on arrhythmias induced by cerebral ischemia and ouabain in Mongolian gerbils]

Changes in the electrocardiogram following bilateral common carotid arteries ligation was observed during the awake state and pentobarbital anesthesia; and the influences of cerebral ischemia, pentobarbital or halothane anesthesia on the cardiotoxicity induced by continuous infusion of ouabain were also studied in Mongolian gerbils. Following ligation, all awake-animals died in about 60 min of ligation, all exhibiting severe neurological symptoms and ventricular arrhythmias. These changes did not appear in the animals under pentobarbital anesthesia. With regards to the amount of ouabain infusion needed to cause cardiotoxicity in pentobarbital-anesthetized animals, there were no significant differences between the vagus-intact group and the vagotomized group. However, the cardiotoxic dose of ouabain in the ligation group during pentobarbital anesthesia was larger than the cardiotoxic dose in the non-ligation group. In halothane anesthesia, the cardiotoxic dose of ouabain decreased more prominently than in pentobarbital anesthesia. The arrhythmias observed with isoproterenol were not enhanced by the halothane anesthesia and vagotomy. Therefore, these findings may indicate that during the cerebral ischemia, there is a heterotopic stimulus formation in the impulse conducting system of the heart; ouabain-induced cardiotoxicity appears to be enhancement via ouabain distribution into the cerebrum; and ventricular fibrillation had no definite effect for lowering sensitization of the myocardium to catecholamine by halothane in Mongolian gerbils.