Effect of urea on central nervous system activity in the cat

Abstract

Effects of i.v. infusion of urea were studied in 26 cats by recording spontaneous cortical activity and somatic afferent evoked potentials from the posteroventral lateral nucleus of the thalamus and periaqueductal midbrain reticular formation. Subsequent to the administration of a 20% solution of urea, spindling and seizure discharges appeared in the electrocorticogram. The evoked potentials from the posteroventral lateral nucleus of the thalamus and reticular formation remained unchanged. Control studies indicated that the operative procedure, including the insertion of subcortical electrodes, hydration incident to fluid administration, possible deterioration of the preparation and alteration of the osmolarity of the serum did not produce the observed results. It was demonstrated that urea administered intravenously, in amounts producing blood NPN values commensurate with those observed in patients with uremia, alters cortical activity and excitability.

Urea-Induced Myoclonic Seizures

“…Sometimes the separation of dis¬ charging units was 200/x to 250/x. (2) The pattern of discharges (whether sponta¬ neous or induced by reticular, pyramidal, or proprioceptive stimulation) was usually composed of spikes separated by intervals sufficiently long enough to assume genera¬ tion by independent excitatory postsynaptic potentials (EPSP). In 40 cells in which the electrode was sufficiently discriminating and close enough to the cell to record the EPSP, this characteristic was very clear.…”