Development of a sensitive radioimmunoassay for IGF-I determination in samples from blood plasma and cell-conditioned medium

This paper describes the development of a versatile non-equilibrium RIA for measurement of IGF-I concentrations in animal samples obtained from both b t vivo and in vitro sources. Assay parameters for this IGF-I RIA indicated that the assay is accurate (96.2% of IGF-I recovery), precise (intra- and i nterassay coefficients of variation < 10 and 16% resp.) and sensitive (0.1 ng/ml at the 95% confidence limit). Determination of IGF-I concentration in blood plasma of sheep and nutria, serum of adult goat and bovine fetuses, as well as in bovine and nutria granulosa cell-conditioned medium demonstra ted the validity of this assay system. From the results, we conclude that t his IGF-I assay will be useful for analysis of samples obtained from Bt viv o or in vitro systems.