Non-suppressible insulin-like activity during acute metabolic and endocrine changes in dogs

Non-suppressible insulin-like activity (NSILA-S) was determined in dogs after acute changes in the blood sugar and after injection of growth hormone. Serum was chromatographed over Sephadex G-50 columns equilibrated in 1 M acetic acid and NSILA-S was determined in the fractions between 55 and 85% column volume using a protein binding assay and the conventional fat pad assay. The results obtained with these two methods correlated rather well (r = 0.74). Hyperglycaemia induced by an intravenous glucose load, by intravenous administration of mannoheptulose or both was not followed by an increase in NSILA-S levels. The injection of insulin and human growth hormone did not lead to alterations of the NSILA-S levels. It is concluded that total NSILA-S levels in the dog do not change acutely following manipulations of the blood sugar and that, in all likelihood, NSILA-S plays no role in the regulation of blood glucose.