Biological activity of glucose tolerance factor in swine.

In vitro incubation of swine adipose tissue slices in the presence or absence of insulin with a synthetic glucose tolerance factor (GTF) did not increase glucose utilization for oxidative metabolism or lipogenesis. GTF had no effect on glucose clearance rate or peak insulin response following an intravenous glucose challenge. Based on the glucose clearance rate and nominal stimulation of insulin release, swine have a very efficient glucose homeostatic mechanism. GTF did potentiate the hypoglycemic response following an intravenous insulin challenge. This latter observation indicates that GTF is biologically active in swine and is consistent with the hypothesis that the compound potentiates the insulin-insulin receptor interaction and subsequent biological response. Although GTF is biologically active in swine, the inclusion of trivalent chromium as an essential dietary trace element for swine would be speculative unless a true dietary deficiency of chromium can be demonstrated. (