Autonomic dysfunction in epilepsy: characterization of autonomic cardiac neural discharge associated with pentylenetetrazol-induced epileptogenic activity
Lathers CM and Schraeder PL (1982) Autonomic dysfunction in epilepsy: Characterization of autonomic cardiac neural discharge associated with pentylenetetrazol-induced epileptogenic activity. Epilepsia 23:6 633–47.
Abstract: The purpose of this study was to determine if epileptogenic activity is associated with changes in autonomic cardiac neural discharge and the development of arrhythmias. Nine cats, anesthetized with alpha-chloralose, received pentylenetetrazol (PTZ), 10, 20, 50, 100, 200, and 2,000 mg/kg, intravenously at 10 min intervals. The following were monitored: neural discharge from 1 to 3 postganglionic cardiac sympathetic branches (8 cats, 17 nerves) and the vagus (7 cats, 8 nerves); the electrocorticogram; blood pressure; heart rate; and lead II electrocardiogram. Autonomic dysfunction was manifested by: the observation that autonomic cardiac nerves did not always respond in a predictable manner to changes in blood pressure; the development of a marked increase in variability in mean autonomic cardiac sympathetic and parasympathetic neural discharge; and the fact that the very large increase in the variability of the discharge rate of parasympathetic nerves was seen after PTZ, 50 mg/kg, but did not develop until 100 mg/kg in sympathetic neural discharge. This autonomic imbalance was associated with both interictal and ictal epileptogenic activity. Almost invariably, interictal discharge occurred after PTZ, 10 mg/kg; with higher doses, the duration of ictal activity increased although interictal discharges were present. The altered cardiac autonomic neural discharge was associated with minimal epileptogenic activity in the form of interictal discharges and cardiac arrhythmias which may contribute to sudden unexplained death of the epileptic.
Keywords: autonomic dysfunction, pentylenetatrazol, cardiac autonomic nerves, heart rhythm, mean arterial blood pressure
Context
- Animal study in cat monitoring autonomic activity following administration of pentylenetetrazol under anesthesia. Auotonomic input to the heart became more variable after seizure, but occurred at different dosages for parasympathetic and sympathetic input (‘autonomic imbalance’). A large variability between effects on sympathetic nerves was observed in the same animal.