INHIBITION OF ACIDIFICATION RATE IN CULTURED FIBROBLASTS BY GLUCOCORTICOIDS - APPLICATION OF SILICON MICROPHYSIOMETRY TO ENDOCRINOLOGY

A recently-developed semiconducter-based instrument, the silicon micro physiometer, allows for real-time, sensitive quantification of cellula r metabolism in small numbers of cultured cells with relative ease. Th is is accomplished by detecting the extrusion into the extracellular s pace of acidic metabolic products of glycolysis, respiration, and ATP hydrolysis, including lactic acid, CO2, and protons. In the present re port, we use microphysiometry to observe that glucocorticoids inhibit metabolic rate (as assessed indirectly by a change in the extracellula r acidification rate) in fibroblasts (minimal effective dose of 1 nM o f corticosterone), whereas 1 muM each estradiol, progesterone and test osterone failed to do so. We suggest that this inhibition of metabolis m is secondary to the well-established inhibition of glucose transport and of protein synthesis in fibroblasts by glucocorticoids.