Inhibition of acidification rate in cultured fibroblasts by glucocorticoids. Application of silicon microphysiometry to endocrinology.

A recently-developed semiconductor-based instrument, the silicon microphysiometer, allows for realtime, sensitive quantification of cellular metabolism in small numbers of cultured cells with relative case. This is accomplished by detecting the extrusion into the extracellular space of acidic metabolic products of glycolysis, respiration, and ATP hydrolysis, including lactic acid, CO2, and protons. In the present report, we use microphysiometry to observe that glucocorticoids inhibit metabolic rate (as assessed indirectly by a change in the extracellular acidification rate) in fibroblasts (minimal effective dose of 1 nM of corticosterone), whereas 1 microM each estradiol, progesterone and testosterone failed to do so. We suggest that this inhibition of metabolism is secondary to the well-established inhibition of glucose transport and of protein synthesis in fibroblasts by glucocorticoids.