Fig. 4

Spontaneous entry into VF and conversion with VNS. EKG and BP tracings for a rat that underwent autonomic activation/hypoxia induced VF and VNS defibrillation are shown in (a). The rat was infused with isoproterenol 26 mg/kg. Four milliliters of dead space tubing were placed over the endotracheal tube for 38 s before fibrillation. In (b), the M-mode image of a different rat undergoing the same type of fibrillation is shown. The rat was infused with isoproterenol 30 mg/kg and had a 6-ml dead space placed over the endotracheal tube for 65 s before fibrillation. The dead space was removed after the period shown in the image. In both (a) and (b), the right vagus was stimulated with 3.5-mA, 1-ms pulses at 50 Hz to defibrillate