The effect of various hepatic vein pressures on hepatic hemodynamics, on fluid shifts within the liver, and on certain indices of liver function were studied in the isolated rat liver preparation. In general, venous pressures are scarcely perceived by the hepatic parenchyma unless they exceed the hydrostatic pressures acting at the liver surface, more particularly at the hilum of the liver. Venous pressures exceeding this value appear to distend the liver vasculature so that it acts like a system of rigid conduits; there is great expansion of the sodium space and of the colloid distribution spaces, and some evidence of partial sequestration of blood in the congested liver. All these changes impair oxygen supply to the tissue. To a lesser extent they interfere with the transfer of other substances from blood to parenchyma, and place considerable stress upon the mechanical framework of the liver. The resulting strain in turn tends to limit the extent of intrahepatic changes in passive congestion, and possibly the rate of fluid leakage from blood via parenchyma to transudate at the liver surface.
P32-labeled chromic phosphate colloid disappears from the circulation of the isolated rat liver preparation according to a single exponential term of time. A small nonextracted contaminant, less than 3% of the total activity is also detected. At comparable blood flow rates the colloid is extracted about as completely by the isolated liver preparation as by the liver in situ in the intact animal. The efficiency with which chromic phosphate colloid is removed from perfusate passing through the isolated rat liver decreases with increasing perfusion rate. If whole blood is used as a perfusate, the efficiency of colloid extraction is almost twice as high as it is if rat blood plasma is employed, even if adequate oxygenation of the tissue is assured by high oxygen partial pressures in the latter series. A theoretical treatment of these results is given in terms of first order reaction kinetics. Agreement of experimental results with this theory at perfusion rates greater than 2 cc/gm/min. indicates that the rate of chromic phosphate colloid extraction is a function of plasma concentration of the colloid, and that the extraction efficiency for a given perfusate varies as a function of the mean transit time of perfusate through the liver. Deviations from the predictions of the theory occur at low perfusion rates, and are discussed in the light of the above concepts. A decrease of the ratio of transit time to perfusion rate under these conditions suggests a decrease in the number of channels open to blood flow at low perfusion pressures.
The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.