7 nm versus 89 ± 1.3 nm; p < 0.05), median (94 ± 1.8 nm versus 100 ± 1.3 nm; p < 0.05), percentile 75 (107 ± 2.3 nm versus 113 ± 1.4 nm; p < 0.05) and percentile 90 values (122 ± 3.2 nm versus 130 ± 1.4; p < 0.05 nm) in ethanol-treated rabbits compared to control rabbits. Figure 2 Transmission electron micrograph of liver sinusoidal endothelial fenestrae in New Zealand White rabbits. The GW786034 in vitro endothelial lining is cut tangentially and shows the occurrence of fenestrae (f) mostly in groups, called sieve plates. To the left and the right hand side of the picture, we find the space of Disse
(Sd) with sparse microvilli (mv) protruding from parenchymal cells. The right top corner of the picture shows the lumen (L) of the sinusoid. The right bottom part of the picture shows the cytoplasm of a parenchymal cell. Figure 3 Frequency distribution histograms of the diameter of liver sinusoidal endothelial fenestrae in New Zealand White rabbits. Comparison of the frequency distribution histograms of the size of sinusoidal fenestrae in New Zealand White control rabbits
(black bars; n = 8) and New Zealand White rabbits injected with 0.75 g/kg ethanol 10 minutes before perfusion fixation (white bars; n = 5). Each bar corresponds to a 5 CCI-779 mw nm interval. Discussion The current study, using lege artis transmission electron microscopy measurements, shows that ethanol at toxicologically relevant levels significantly decreases the diameter of fenestrae in New Zealand White rabbits. Since this effect was observed ten minutes after ethanol injection, this study is in line with the view that the liver sinusoidal endothelial cells are the first hepatic cells that undergo morphological changes in alcoholemia [1]. Both endothelin-1 and NO may play a role in the effect of ethanol on the diameter of fenestrae. Previously, it has been demonstrated that ethanol induces hepatic vasoconstriction in isolated perfused rat liver and that endothelin-1 antibodies significantly inhibit this ethanol-induced hepatic vasoconstriction [12]. Since endothelin-1 has been shown to induce contraction Vasopressin Receptor of hepatic sinusoidal endothelial fenestrae [13], endothelin-1 may mediate the
decrease of the diameter of fenestrae after ethanol injection. Although hepatic vasoconstriction in isolated perfused rat liver persists during ethanol exposure, portal pressure gradually decreases [12]. This attenuation of ethanol induced vasoconstriction is mediated by NO[12]. Similarly, NO may oppose the contraction of hepatic sinusoidal endothelial fenestrae by endothelin-1: it induces a decrease in the cytosolic free calcium concentration Erastin leading to the dissociation of calcium and calmodulin from the myosin light chain kinase. Under these conditions, myosin light chain phosphatase dephosphorylates the myosin light chain and causes relaxation of fenestrae [14]. NO bioavailability in the sinusoid in the presence of ethanol will depend on two opposing factors.