AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 6 1033-R1039, Copyright © 1992 by American Physiological Society
Changes in insulin sensitivity from stress during repetitive sampling in anesthetized rats
R. H. Rao
Department of Medicine, Montefiore University Hospital, University of Pittsburgh School of Medicine, Pennsylvania 15213.
The effect of repetitive sampling on insulin sensitivity was studied in
anesthetized rats. During glucose clamp studies, glucose disposal decreased
from 9.3 +/- 0.9 (SE) to 6.5 +/- 1.1 mg.kg-1.min-1 (P less than 0.05), and
hepatic glucose output (HGO) increased from 1.2 +/- 0.8 to 2.4 +/- 1.1
mg.kg-1.min-1 (P less than 0.05) after a cumulative blood loss of 9 ml/kg.
After a loss of 15 ml/kg, HGO rose further to 4.7 +/- 1.6 mg.kg-1.min-1 (P
less than 0.05). During repetitive sampling under identical conditions,
plasma adrenocorticotropic hormone (ACTH) increased, despite simultaneous
saline infusion, from 68 +/- 11 to 102 +/- 15 pg/ml (P less than 0.05) with
a loss of 8 ml/kg, while plasma insulin increased from 39 +/- 7 to 124 +/-
20 mU/l (P less than 0.01) with a loss of 10 ml/kg. Thereafter, ACTH and
insulin rose progressively. Plasma corticosterone closely followed the
pattern of the ACTH response, indicating that the stress of cumulative
blood loss had a significant effect on adrenal steroid production.
Increases in ACTH were retarded by reduced volume loss and accelerated by
increased loss. It is concluded that stress from blood loss greater than 7
ml/kg may be a source of error in the evaluation of glucose turnover and
insulin sensitivity during clamp experiments in rats.
