The plasma glucose profile of individual rats in response to a single subcutaneous injection of streptozotocin

We employed a permanently indwelling jugular cannula to obtain serial blood samples from individual, freely moving, conscious rats, Blood glucose levels were measured 1, 2, 4, 6, 8, 10, 12, 18 and 24 h following a single subcutaneous injection of the diabetogenic agent streptozotocin (60 mg kg(-1)). Streptozotocin administration resulted in a hyperglycaemia of short duration (1 h), a hypoglycaemic phase lasting from 6 up to 10 h following injection and finally a hyperglycaemia which was evident from 12 h onwards. This triphasic response was not uniform in all rats. While there was only slight individual variation in the early hyperglycaemia, the length of the hypoglycaemic phase was between 4 and 10 h. This method of obtaining blood samples allowed us to monitor the blood glucose response in individual animals and to obtain blood samples at frequent time intervals.