Assays microphysiometer

Functional assays such as Ca2+ mobilization and chemotaxis (see Chapters 16 and 11 respectively, in this volume) or microphysiometer analysis (4) in response to ligand stimulation. 

The Cytosensor Microphysiometer (CM) test method is currently under discussion (draft test guideline on the Cytosensor Microphysiometer) at OECD level [34], It is a cytotoxicity and cell-function based in vitro assay that is performed on a sub-confluent monolayer of adherent mouse L929 fibroblasts cultured in a sensor chamber using a pH-meter to detect changes in acidity [35]. The CM test method serves as an in vitro model system for the cytotoxic action of a test chemical on the cell membranes of the corneal and conjunctival epithelium where the irritant chemical would be... 

A more recent cell-based in vitro assay involves the use of the microphysiometer, a sensitive extracellular pH sensor, which has been used to measure luminal (or apical) secretion and basolateral release of OH- as well as liberation of acidic metabolites in rabbit gastric glands. Adenosine 3, 5 -cyclic monophosphate stimulation produced a biphasic change... 

Compound 6m, a chiral molecule, was resolved and the enantiomers, (R)-6m (CI-1017) and (S)-6m, evaluated for muscarinic receptor subtype selectivity in a battery of in vitro and in vivo assays (Tables 9-12). The effect of the enantiomers on receptor-mediated cellular metabolism of Hm, Hm2, Hmj, and Hm4 CHO cells was measured (Table 9). Enhanced cellular metabolism results in increased acidification of environment of the cells which can be measured by a microphysiometer. The results show that 6m and its enantiomers have no efficacy at M2 receptors. The enantiomer (R)-6m is M[-selective and at non-M2 receptors, it is 5- to 10-fold more potent than the (5)-6m enantiomer. 

Cooke, D. and O Kennedy, R. (1999). Comparison of the detrazoHum salt assay for succinate dehydrogenase with the cytosensor microphysiometer in the assessment of compound toxicities. Anal. Biochem. 274 188-194. 

---