EFFECT OF HYPOTHERMIA ON METABOLISM AND DRUG 



DETOXIFICATION IN THE ISOLATED PERFUSED 



RABBIT LIVER 



IRVING GRAY, ROLAND R. RUECKERT and RICHARD R. RINK 



Perfusion of the isolated liver has been used by a number of investigators, 

 particularly in the past five years. ^"'^ Prudden and co-workers" have used this 

 method in the study of the effects of insulin and growth hormone on liver metab- 

 olism. Miller ct al. reported in 1954 that perfusion of the intact-isolated liver 

 with oxygenated blood permits the liver to synthesize plasma proteins, to separate 

 them from its own tissue at need, and to contribute them to the circulating plasma 

 in a manner closely approximating that seen in intact normal animals.' They also 

 reported that the perfused liver repeats its action quantitatively when a second dose 

 of substrate is given, even after having been perfused for four hours." 



With the advent of surgery under hypothermic conditions, it was felt that the 

 liver perfusion method for the study of metabolism and detoxification would 

 yield valuable information for this clinical problem. The present study utilized this 

 technique as an in vitro method of ol)serving the effect of hypothermia on liver 

 respiration, metabolism and its ability to conjugate morphine and thiopental. In 

 addition to the usual methods for measuring carbon dioxide production and rate of 

 drug detoxification, the apparatus has been so designed as to allow the measurement 

 of oxygen consumption. 



Description of apparatus. The liver perfusion apparatus described in this 

 report measures volumetrically the oxygen uptake of the perfused organ by recir- 

 culating the gas mixture in a closed system. It is a modification of perfusion equip- 

 ment previously described.'' ' The apparatus is enclosed in a thermoregulated 

 cabinet.* The system consists essentially of three components : A pumj) which main- 

 tains blood flow; a "lung" which \entikites the blood and an organ which utilizes 

 this blood (fig. 1). 



The circuit of the perfusion fluid is conveniently traced l^eginning with the 

 reservoir flask from which the perfusate is lifted through a filter to remove any 

 clots that may form during the experiment. The pump, a Brewer pipetting machine, 

 with variable speed and stroke, activates a finger-stall pump. Uni-directional flow is 

 obtained by attaching glass perfusion valves to the finger-stall i)ump. From this 

 point blood passes to the top of a condenser column that functions as an artificial 

 lung. The l)lood is spilled from the top of the "lung" as a thin, falling iilm ])assing 

 counter-current to a stream of oxygen which oxygenates the blood and sweeps it 

 free of its load of carbon dioxide. The "arterial" blood is collected in a small 

 reservoir at the base of the "lung" where two outlets are provided, one channeling 

 blood to the portal vein cannula, and the other serving as an overflow returning 

 surplus blood to the reservoir flask. This overflow outlet is suspended 20 cm. above 

 the liver, thereby ])roviding a constant ])erfusion pressure. Oxygenated blood. 



* Fal)rii-atcd hy Gt'iioral .Service Division, Carpenter Simp, Walter Reed Army institute of 

 Research, Walter Rvcd Army .Medical Center, VVashin.ntim 12, D.C. 



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