Alteration of Plasma Insulin and Glucagon Responses to Arginine in Diabetic Rats with Pancreas Isografts

Abstract

Whole pancreas of an adult male rat (Lewis strain) was isografted to a streptozotocin-induced diabetic rat using Lee-Nozawa's techniques. In order to elucidate the endocrine function after isografting, changes in blood glucose and the arginine (100 mg/kg, iv)-induced plasma insulin and glucagon responses were determined. Blood glucose was measured by the glucose-oxidase method, and plasma insulin by polyethylene glycol radioimmunoassay using rat insulin as standard. Plasma glucagon was determined by a radioimmunoassay in which 30 K was used as antiserum.
The results obtained may be summarized as follows:
1) The fasting blood glucose in streptozotocin diabetic rats was significantly higher than that of normal rats. The responses of arginine-induced plasma insulin in streptozotocin diabetic rats were significantly impaired, compared to those of normal rats.
2) No significant difference in basal plasma glucagon levels was observed between streptozotocin diabetic and normal control rats, although hyperglycemia was observed in the former.
3) In streptozotocin diabetic rats after the transplantation, the fasting blood glucose level was significantly lowered to a normal level and the arginine-induced insulin response showed significant improvement.
4) The plasma glucagon response to arginine in diabetic rats with transplanted pancreas was significantly higher than that of normal rats.
The above results suggest that whole pancreas transplantation in experimental diabetic rats may represent a useful tool for investigating the pathogenesis and treatment of diabetes mellitus in man.