Correlation between glucose basal uptake and insulin effect in rat-diaphragm method.

For the microdetermination of insulin, various biological standardizations have been attempted.Recently the application of the rat-diaphragm method was introduced(Vallance-Owen and Hurlock, 1954;Randle, 1954;Takeuchi et al., 1957a). The advantage of this latter over others is that the minimum detectable concentration is very low; that is, 0.01-0.001mU per ml can be detected. The results obtained by many investigators, however, are not always in agreement with each other, for the insulin activity in plasma as well as for the properties of the log dose response curve which is applied to the bioassay of insulin.This seems to indicate that,in the determination by this method up to the present,each detail of the procedure has not been perfectly followed under optimal conditions.Lately, one of the authors,Takeuchi(1958), published the results of a detailed investigation on these points, but nevertheless they are not yet completely clarified.Nowwith the object of establishing a consistent and reliable estimation by the diaphragm method,some investigations have been carried out from the viewpoint that the basal uptake and the insulin effect must be correlated with each other, and consequently that there must be an intimate relationship between various experimental conditions.The present paper is intended to outline these experiments,which revealed some facts of interest.