Circulating NSILA-s in man: Preliminary studies of stimuli in vivo and of binding to plasma components.
The insulin-like peptide NSILA-s (non-suppressible insulin-like activity soluble in acid ethanol) was measured in plasma using gel filtration in acid and a new radioreceptor assay. Total plasma NSILA-s levels, which are elevated in some patients with extrapancreatic tumors and hypoglycemia, were also found to be elevated in pregnancy. Patients with hypopituitarism had subnormal concentrations of total plasma NSILA-s which rose promptly and reached a peak 1 h after intravenous hGH. In contrast ot this acute stimulus, chronic elevation of hGH resulted in an elevated level of NSILA-s in only 1 of 10 acromegalics. In normal subjects, oral glucose loading resulted in a rise in NSILA-s (mean peak equals 151% of basal) while insulin induced hypoglycemia produced a small and variable fall. Among the other conditions studied, anorexia nervosa was associated with low levels of NSILA-s. Using gel filtration we found that at physiologic pH about 93% of endogenous NSILA-s is reversibly bound to larger molecules. We show that in normal adults the insulin-like bioactivity in plasma due to free NSILA-s in the basal state is equal to that exerted by insulin itself, and that the free NSILA-s in the circulation of patients with extra-pancreatic tumors approximates the elevated level of insulin in patients with insulin-secreting pancreatic tumors.
D000172:Acromegaly / Q000378:metabolism; D000856:Anorexia Nervosa / Q000378:metabolism; D001786:Blood Glucose; D005260:Female; D005354:Fibrosarcoma / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D007003:Hypoglycemia / Q000378:metabolism; D007018:Hypopituitarism / Q000378:metabolism; D007328:Insulin / Q000097:blood*; D010455:Peptides / Q000097:blood*; D011247:Pregnancy; D011485:Protein Binding; D011956:Receptors, Cell Surface
D001786:Blood Glucose; D007328:Insulin; D010455:Peptides; D011956:Receptors, Cell Surface; D013006:Growth Hormone