Rat C peptide I and II stimulate glucose utilization in STZ-induced diabetic rats

• DOI: 10.1007/s001250051254
• Publication Date: 2002-08-25T03:30:30Z
• Authors: L. Li; Y. Oshida; M. Kusunoki; K. Yamanouchi; B.-L. Johansson; J. Wahren; Y. Sato
• Keywords: Blood Glucose; Male; C-Peptide; Insulin, Regular, Pork; Diabetes Mellitus, Experimental; Rats; Kinetics; 03 medical and health sciences; Glucose; 0302 clinical medicine; Reference Values; Glucose Clamp Technique; Animals; Hypoglycemic Agents; Insulin; Rats, Wistar; Infusions, Intravenous

To study the effects of physiological concentrations of rat proinsulin C peptide I and II, respectively, on whole body glucose utilization in streptozotocin diabetic and healthy rats.A sequential insulin clamp procedure was used (insulin infusion rates 3.0 and 30.0 mU.kg-1.min-1) in awake animals. C-peptide infusion rates were 0.05 and 0.5 nmol.kg-1.min-1. Blood glucose was clamped at 7.7 +/- 0.3 mmol/l in the diabetic rats and at 3.9 +/- 0.1 mmol/l in the healthy rats.In diabetic rats infused at lower rates of C peptide and insulin, glucose utilization increased by 79-90% (p < 0.001) compared with diabetic animals infused with saline and insulin. Increasing the rate of C-peptide infusion tenfold did not elicit a statistically significant further increase in glucose utilization. C peptide I and II exerted similar effects. The metabolic clearance rate for glucose in the diabetic animals infused with C peptide was not different from that of the healthy rats. During high-dose insulin infusion (30.0 mU.kg-1.min-1) glucose utilization increased considerably and no statistically significant C-peptide effects were observed. About 85% of the increase in glucose utilization induced by C peptide could be blocked by treatment with N-monomethyl-L-arginine.Physiological concentrations of homologous C peptide stimulate whole body glucose utilization in diabetic but not in healthy rats. C peptide I and II elicit similar effects. The influence of C peptide on glucose utilization may be mediated by nitric oxide.