MORPHOLOGICAL CHANGES AND CYTOTOXICITY IN ISOLATED HEPATOCYTES

Cells exposed to different types of stress usually exhibit morphological changes. These changes are often referred to as cell blebbing. The aim of this study was to compare a few different cytotoxins acting on freshly isolated rat hepatocytes through different molecular mechanisms. The toxins used were phalloidin and cytochalasin D (for cytoskeletal alterations), menadione (for oxidative stress), the Ca2+-ionophore A23187 (for intracellular Ca2+-elevation) and microcystin-LR (for protein phosphatase inhibition). Light and electron microscopy were used when comparing the morphological effects of the toxins. The morphological effects on microfilaments were studied by labelling F-actin with rhodamine-conjugated phalloidin. The results indicate that, although all the toxins caused cell blebbing, the blebs were morphologically markedly different and the redistribution of actin varied considerably, depending on the toxin used. The modification of the microfilamental architecture seemed to correlate with the morphological changes. Cell blebbing is inevitably a rather vague term for morphological alterations, which may look very different, depending on the subcellular cytotoxic mechanism involved.