Experimental Acute Hepatic Encephalopathy: Comparison of the Electroencephalographic Changes in the Liverless and in the Eviscerated Rat

Abstract

1. The present work was carried out to compare the electroencephalographic changes in liverless rats and eviscerated rats and to determine whether substances released from the intestine, in particular ammonia, play a major part in the mechanism of hepatic encephalopathy.2. The animals were prepared according to a three-stage procedure: ligation of inferior vena cava; 3 weeks later, end-to-side portacaval shunt ; 2 days later, removal of the liver (liverless rats) or removal of the liver, spleen, stomach, intestine and pancreas (eviscerated rats).3. In liverless rats, the electroencephalographic changes began 4-8 h after hepatectomy with a predominance of 'slow' sleep pattern followed by increasing changes, which consisted successively of (a) alteration of, then disappearance of, spindles of high-voltage waves; (b) predominance of slow waves; (c) depression in voltage and finally flat tracing. The mean duration of survival was 18.4 h. Mean plasma ammonia concentration 15 h after hepatectomy was 353 ymolll.4. In eviscerated rats, the electroencephalographic changes were similar. The mean duration of survival was 21-3 h, which is not statistically different from that of liverless rats. Mean plasma ammonia concentration 15 h after evisceration was 148 pmolll, a value significantly lower than that of liverless rats.5. These results suggest that ammonia, and substances released from the intestine in general, play no part or at most a minor role in the mechanism of hepatic encephalopathy of the liverless rat. F 599 SVEDBERG, A., MADDOCK, S. & DRURY, D.D. (1938) The effect of total removal of the liver in the rabbit.

Acute Hepatic Encephalopathy in the Rat: The Effect of Cross-Circulation

“…Liverless rats were prepared according to a procedure described previously (Degos et al, 1974). Immediately after hepatectomy, a polyethylene catheter of 1.70 mm external diameter and 1.19 mm internal diameter (catheter no.…”

“…60217501; Lepetit, Suresnes, France) were inserted respectively in the aorta and in the jugular vein. Adequate amounts of glucose were infused intravenously in order to prevent hypoglycaemia (Degos et al, 1974). The animals were immobilized in restraining cages and placed in a constant-temperatrue room to maintain rectal temperature at 26°C.…”

“…The animals were immobilized in restraining cages and placed in a constant-temperatrue room to maintain rectal temperature at 26°C. EEG was obtained through four electrodes, which had been implanted through the skull in contact with brain: two electrodes were placed symmetrically on the frontal cortex, and two on the parietal cortex; a longitudinal, frontal-parietal, derivation and a transverse, parietal-parietal, derivation were continuously recorded (Degos et al, 1974).…”

“…hepatic encephalopathy which has been designed in this laboratory (Degos, Degos, Bourdiau, Peignoux, Prandi, Roche-Sicot, Sicot, Rueff & Benhamou, 1974): in the rat, total hepatectomy results in a type of brain dysfunction that can be objectively evaluated by electroencephalography (EEG). The specific purposes of this work were: (1) to evaluate the possible influence of the exchange-flow rate of CC between a normal and a liverless rat on the EEG alterations after hepatectomy, and (2) to compare the respective efficiency of systemic-systemic and systemicportal CC.…”