Electroencephalogram in ruminants. 3. Effect of experimental hyperammonemia on the REG in goats

Abstract

Electroencephalograms (EEGs) were recorded bipolarly from the frontal andparietal cortical regions in 7 female goats. Silver balls (1 mm in diameter) were usedas electrodes and implanted chronically on the cerebral dura mater through a small holeof the skull. Experiments were carried out to clarify the effect of experimental hyper-ammonemia on the EEG in goats.l. When ammonium chloride (aqueous solution) was injected in an amount of0.5 milli-molecules (ml) per kg of body weight into the anterior vena cava through apolyethylene cannula, the blood ammonia concentration increased rapidly. On theEEG there appeared high-amplitude slow waves (2O0s4O0pV, 4x5 c/s) at a durationof 2 to 3 seconds and an interval of 10 to 20 seconds. This pattern was induced when theblood ammonia concentration exceeded 500pg per TOO ml of blood. There was anincrease in duration and frequerncy of appearance of this pattern with an increase indose of ammonia.2.. When ammonium chloride was infused into the anterior vena cava at a rateof 0.033 mlVI per minute per kg of body weight for 60 minutes, the blood ammoniaconcentration increased gradually, and high-amplitude slow waves tended to appear.When it was infused at a rate of 0.05 ml per minute per kg of body weight, there wasa rapid increase in this concentration and induced pattern appeared. When the bloodammonia concentration was high and the respiratory movement was in a critical state, however, low-amplitude fast waves were observed on the pattern.3. When urea was injected in a dose of 3 to 12 mM per kg of body weight intothe anterior vena cava, no induced pattern appeared at all.4. When urea was infused in a dose of 4 ml per kg of body weight irtto therumen through a permanent fistula, the induced pattern appeared.5. When crystalline urea was mixed with powdered food and fed at a rate of6 ml per kg of body weight, it was a little slower in sltowing an effect than when itsaqueous solution was infused into the rumen, there was an increase in blood ammoniaconcentration and tlae induced pat