Abstract
The fibrosis that accompanies hepatic cirrhosis, either that produced in animals experimentally (for example, by CCI4, ethionine, or choline-free diet) or that occurring in man (viral, alcoholic-nutritional or biliary) is one of the main features of the diseas.
Two mechanisms have been proposed for the development of fibrosis: (a) condensation or collapse of preexisting hepatic stroma (2), and (b) induction of fibroblastic proliferation and de novo collagen deposition (5). The latter mechanism is supported by evidence showing a net increase of total collagen content or an increase of hydroxyproline content per unit weight of liver (3, 7). The present experimens were designed to explore the capacities of normal and cirrhotic rat liver slices to synthesize protein containing radioactive hydroxyproline in the course of incubation with labeled proline.
Materials and Methods. Male Wistar albino rats weighing from 60 to 70 g were fed ad libitum with Purina chow. Cirrhosis was produced by intraperitoneal injection, 3 times/week, of 0.15 ml of a 1:7 solution of CC14 in mineral oil; each rat received a total of 20 injections.
Two days after receiving the last injection, a rat was deprived of food but not of water during 16 hr. It was stunned by a sharp blow to the head, decapitated, and the liver was removed to ice-cold Ringer-NaHCO3 buffer. Thin slices were cut by hand, and a pool was made of liver slices from 5 rats. The slices were washed twice with cold buffer and then incubated for 4 hr in Erlenmeyer flasks under an atmosphere of O2:CO2 (95:5%), at 37° in a Dubnoff shaking incubator at 100 cycles/min.
The incubation medium contained per flask: 1 g of liver slices, 2.5 ml of buffer and 5 μCi (0.5 ml) of uniformly labeled proline-14C [The Radiochemical Centre, Amersham, Bucks; sp act, 120 mCi/mmole]. Zero-time controls contained, in addition to the former, 20 μmoles of KCN.
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