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THE ISOLATED PERFUSED LIVER OF THE SHEEP: AN ASSESSMENT OF ITS METABOLIC, SYNTHETIC AND EXCRETORY FUNCTIONS
Author(s) -
Linzell J. L.,
Setchell B. P.,
Lindsay D. B.
Publication year - 1971
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1971.sp002098
Subject(s) - perfusion , glycogen , endocrinology , medicine , propionate , urea , artery , blood flow , chemistry , biology , biochemistry
A technique is described for perfusing in isolation the livers of Soay sheep. Thirty‐two livers were perfused for 3–8·5 hr and their normality assessed by histology and by measuring blood and bile flow, Bromsulphthalein (B.S.P.) clearance, the uptake of O 2 and infused NH 3 and propionate, the production of CO 2 , urea and glucose and changes in tissue glycogen and weight. With portal pressure set below 10 mm Hg and arterial pressure set at l10 mm Hg, blood flow was 90–400 ml./100 g/min, 3–35 per cent of which came from the hepatic artery. Stimulation of nerves around the hepatic artery caused vasoconstriction in hepatic and portal vascular beds. Maximum bile flow during perfusion was similar to pre‐perfusion values, but generally declined to 20–75 per cent. The extraction of B.S.P. from the blood was inversely related to total blood flow, but directly to the hepatic artery flow. The percentage of injected B.S.P. appearing in the bile was related to bile flow. Perfused livers appeared normal histologically but small amounts of GOT (aspartate amino transferase) were released into the perfusate continually. O 2 consumption averaged 1·8 ± 0·21 ml./min/100 g liver with no substrate added to the perfusate and 3·28 ± 0·28 when ammonium propionate was added. Liver glycogen generally (but not invariably), fell during perfusion. Glucose and urea outputs were greatly stimulated by the addition of ammonium propionate to the perfusate, and carbon from 14 C propionate was transferred to glucose and CO 2 . The maximum rate of glucose production from propionate was comparable to that attained in the intact animal, but urea production from ammonia was less than values for the entry rate of urea into the circulation, from all sources, reported in the intact animal. The sheep liver, even when taken from a shot animal, appears to perfuse as well as rat or dog liver, and should be a useful preparation for studying gluconeogenesis and liver function in ruminants.