Affiliation:
1. Laboratory of Surgical Research, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway;
2. Cardiovascular Research Group, Department of Medical Biology, UiT The Arctic University of Norway, Tromsø, Norway;
3. Department of Digestive Surgery, University Hospital of North Norway, Tromsø, Norway; and
4. Department of Laboratory Medicine, Division of Diagnostic Services, University Hospital of North Norway, Tromsø, Norway
Abstract
Development of acute insulin resistance represents a negative factor after surgery, but the underlying mechanisms are not fully understood. We investigated the postoperative changes in insulin sensitivity, mitochondrial function, enzyme activities, and release of reactive oxygen species (ROS) in skeletal muscle and liver in pigs on the 2nd postoperative day after major abdominal surgery. Peripheral and hepatic insulin sensitivity were assessed by d-[6,6-2H2]glucose infusion and hyperinsulinemic euglycemic step clamping. Surgical trauma elicited a decline in peripheral insulin sensitivity (∼34%, P < 0.01), whereas hepatic insulin sensitivity remained unchanged. Intramyofibrillar (IFM) and subsarcolemma mitochondria (SSM) isolated from skeletal muscle showed a postoperative decline in ADP-stimulated respiration (VADP) for pyruvate (∼61%, P < 0.05, and ∼40%, P < 0.001, respectively), whereas VADP for glutamate and palmitoyl-l-carnitine (PC) was unchanged. Mitochondrial leak respiration with PC was increased in SSM (1.9-fold, P < 0.05) and IFM (2.5-fold, P < 0.05), indicating FFA-induced uncoupling. The activity of the pyruvate dehydrogenase complex (PDC) was reduced (∼32%, P < 0.01) and positively correlated to the decline in peripheral insulin sensitivity ( r = 0.748, P < 0.05). All other mitochondrial enzyme activities were unchanged. No changes in mitochondrial function in liver were observed. Mitochondrial H2O2 and O2·− emission was measured spectrofluorometrically, and H2O2 was increased in SSM, IFM, and liver mitochondria (∼2.3-, ∼2.5-, and ∼2.3-fold, respectively, all P < 0.05). We conclude that an impairment in skeletal muscle mitochondrial PDC activity and pyruvate oxidation capacity arises in the postoperative phase along with increased ROS emission, suggesting a link between mitochondrial function and development of acute postoperative insulin resistance.
Funder
Northern Norway Regional Health Authority
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology,Endocrinology, Diabetes and Metabolism