An Improved Assay For Biologically Active Chromium.

Biologically active forms of chromium were measured by determining their insulin potentiation on glucose oxidation by isolated fat cells. Adipocytes were isolated from the epididymal fat tissue of rats maintained on a Cr deficient diet. All natural and synthetic Cr compounds tested that yield real biological activity in previous assay systems were active in the assay. Biologically active organic Cr complexes potentiated the action of insulin more than 300% in this bioassay but inorganic Cr complexes yielded little insulin potentiating activity. Nicotinic acid, which interferes in the assay with fat tissue (Roginski, 1974) gave only a slight positive response in the fat cell assay. Cells isolated from two rats can be used for approximately 150 assays and large numbers of control samples are not needed because individual animal variation within an assay is virtually eliminated. This assay is more sensitive and more reproducible and can be used routinely for more samples than any of the previous assay techniques for biologically active chromium. 19 references, 2 figures.