Effect of insulin and nutrition on serum levels of somatomedin A in the rat.
The serum levels of somatomedin A, as measured by radioreceptor assay, were significantly reduced in rats 2 days after the administration of streptozotocin. The mean decrease was 45.4 +/- 2.9% of the initial values. In rats treated with insulin, blood glucose levels and glycosuria decreased, and serum somatomedin A returned to 108.3% +/- 11.7% of the initial values by the sixth day of treatment. In untreated diabetic rats, serum somatomedin A decreased progressively to 23.4 +/- 4.4% 8 days after streptozotocin administration. The total caloric intakes in the treated and nontreated diabetic rats were similar, suggesting that the low levels of somatomedin A in diabetic rats may be due to lack of insulin. A significant correlation was observed between serum somatomedin A values and body weight (r = 0.90) or the urinary glucose (r = -0.84) or blood glucose levels (r = -0.67). When the diabetic insulin-treated rats were fed a low protein diet, there was no increase in serum somatomedin A. Inhibitory factors in serum which interfere in the bioassay for somatomedin had no effect in our radioreceptor assay.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood*; D004044:Dietary Proteins / Q000008:administration & dosage*; D006029:Glycosuria / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D011869:Radioligand Assay; D051381:Rats; D013002:Somatomedins / Q000097:blood*; D013311:Streptozocin / Q000494:pharmacology
D001786:Blood Glucose; D004044:Dietary Proteins; D007328:Insulin; D013002:Somatomedins; D013311:Streptozocin