Cell viability metabolic markers

Because of the possible effects of active and carrier-mediated processes and metabolic biotransformation, the issue of tissue viability is important for in vitro buccal mucosal experiments. The barrier nature of the buccal mucosa resides in the upper layers of the epithelium, where unlike in the stratum corneum, the cells contain a variety of functional organelles [119, 122, 125, 150], and so tissue viability may be an important component of the barrier function of the tissue. Various methods have been employed to assess the viability of excised buccal mucosa, including measurement of biochemical markers, microscopic methods, and linearity of transport data [42], While biochemical methods, including measurement of adenosine 5 -triphosphate (ATP) levels and utilization of glucose, provide information on the metabolic activity of the tissue, this does not necessarily relate to the barrier function of the tissue. In excised rabbit buccal mucosa, levels of ATP were measured and found to decline by 40% in 6 h, and this correlated well with transmission electron microscopic evaluation of the tissue (intact superficial cells) [32], In addition, the permeability of a model peptide was unaltered up to 6 h postmortem, but at 8 h, a significant change in permeability was observed [32], These investigators therefore claimed that excised rabbit buccal mucosa could be used for diffusion studies for 6 h. 

Of these metabolic analogues, FDG has been the most extensively studied and is the most widely used PET marker of myocardial viability [56]. FDG is transported across the myocyte cell membrane and is phosphorylated by hexokinase. The phos-phorylated compound cannot be metabolized or transported out of the cell and is therefore trapped in the myocyte. However, under some conditions,... 

In another study, primary mammalian hepatocytes isolated from a three-month-old female Lewis rat were cultured on either untreated pSi, fetal bovine serum-treated pSi or coUagen-coated pSi [91 ]. After a 24 h incubation period, measurements of cell adhesion showed the collagennitrogen metabolic pathways, was monitored in the cell culture for 14 days and shown to be comparable to values observed in the presence of polystyrene. Taken together, these data suggest that pSi does not exhibit any significant cytotoxic effects towards primary mammalian cell lines. 

Many complex cell functions, apart from viability and metabolic activities, are assayed using various macromolecular markers. Hence it is important to be able to sample... 

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