Insulin sensitivity tested with a modified euglycemic technique in cats and rats.
A new insulin sensitivity test (IST) is described using a modified euglycemic clamp in cats and rats. The IST uses the amount of glucose required to be infused to maintain euglycemia over a 30-min period in rats and 60 min in cats following a bolus administration of insulin as the index of insulin sensitivity. Glucose levels are determined at short time intervals (2-5 min), and variable glucose infusion is used to hold glucose levels within a few percentage points of the basal pre-test glucose level. A new blood sampling procedure is described that allows each IST to be carried out using a total of only 0.5 mL of blood. The IST is sensitive and allows clear insulin dose effects to be demonstrated with 100 mU/kg requiring 355.0 +/- 14.3 mg/kg over 30 min and 50 mU/kg requiring 198.7 +/- 11.1 mg/kg. Five consecutive tests were reproducibly carried out (%CV = 3.0 +/- 0.5) over a 12-hr period in the cat with insulin, glucagon, and glucose levels remaining stable prior to each IST. Glucagon and norepinephrine plasma concentrations do not change significantly during the IST. The IST is sufficiently sensitive to allow demonstration of dose-response relationships for atropine-induced insulin resistance. The IST is thus sensitive, reproducible, and able to demonstrate acute insulin resistance in anesthetized cats and rats. The test is demonstrated in fed (rats) and fasted (cats) state.
Xie
H
H
Department of Pharmacology & Therapeutics, University of Manitoba, Winnipeg, Canada.
Zhu
L
L
Zhang
Y L
YL
Legare
D J
DJ
Lautt
W W
WW
D000818:Animals; D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism; D002415:Cats; D005260:Female; D015309:Glucose Clamp Technique; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D007328:Insulin / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin