Hepatic Spaces and Transport in the Perfused Liver

Abstract

The liver, in contrast to other organs such as the kidney, is able to extract highly protein-bound compounds. This is related to the particular structure of the liver “capillaries”, the sinusoids. The endothelial lining cell carries sieve-plates with fenestrations permitting exchange of high molecular weight compounds including proteins between the intravascular (sinusoidal) and extravascu1ar space, the space of Disse. The characteristics of these sieve-plates have been assessed by morphometric means by different authors (Wisse et al., 1983; Horn et al., 1986). The average diameter of these fenestrations is 105 and 175 nm, when assessed by scanning and transmission elecron microscopy, respectively; it decreases slightly along the acinus, while the number of fenstrations per square micron increases from 9 to 13 (Wisse et al., 1985). The number and/or diameter of these fenestrations is subject to regulation by different factors (Table 1) including pressure (Nopanitaya et al., 1976, Fraser et al., 1980), alcohol (Mak and Lieber, 1984; Horn et al., 1987), carbon tetrachloride (Okazaki et al., 1973), hypoxia, serotonin, norepinephrine, and cytochalasin B (Stefan et al. 1987).