Studies on the hepatotoxicity of Amanita phalloides in the rat. 1. Liver cell vacuolation

Ultrastructural effects of acetaminophen in isolated mouse hepatocytes

The ultrastructure of isolated mouse hepatocytes shows good correlation with that of cells from intact liver. Incubation of isolated mouse hepatocytes with 1.0 mM acetaminophen causes a variety of cytoplasmic and cell surface lesions, as well as cell death. The changes are similar or equivalent to those caused by acetaminophen in vivo. The most prominent feature of damage in isolated hepatocytes is bleb formation, which is also seen occasionally in control incubations. The protective compound alpha-mercaptopropionylglycine and the antidote N-acetylcysteine both prevented the acetaminophen-induced changes. It is suggested that the in vivo counterpart to the blebs are endocytic vacuoles which form at cell margins due to the intravascular pressure of the sinusoids. It is suggested that the cell surface changes both in vivo and in isolated hepatocytes are caused by some dysfunction to the microfilament component of the cytoskeleton.

Furosemide induced hepatotoxicity

Furosemide-induced (400mg/kg ip) hepatotoxicity progressing to centrilobular necrosis was studied by light and electron microscopy in Swiss white mice. Centrilobular glycogen depletion and cytoplasmic foaminess, usually accompanied by extensive vacuolation, were detectable by light microscopy 1 1/2 hr after furosemide. Centrilobular congestion and hydropic single cell necrosis developed after 3 hr. Electron microscopy revealed disaggregation of polyribosomes, vesiculation of endoplasmic reticulum, an endocytic origin for the vacuolation, and a definite sequence in the development of congestion. Vacuolation coincided with loss of microvilli and resulted in detachment of sinusoidal lining cells from hepatocytes. Small vacuoles apparently formed at the sinusoidal margin of hepatocytes by fusion of microvilli. Congestion and occlusion of sinusoidal lumens developed as a consequence of erythrocytes entering the enlarged Disse space, possibly through pores in the lining cells, and thence entering endocytic vacuoles. The vacuolation, loss of microvilli and terminal hydropic degeneration suggest an important role for the plasma membrane in the development of furosemide-induced hepatotoxicity. Comparisons with known membrane toxins support this concept.