Biomedical subjects

Oivind Irtun

Publications and source records attributed to Oivind Irtun.

4 recordsLinked to original sources

PubMed2002

Both glucose-insulin-potassium and glutamine in warm blood cardioplegia increase the rates of myocardial glucose and free fatty acid oxidation.

OBJECTIVE: We wanted to assess the effect of glucose-insulin-potassium (GIK) and glutamine on the oxidative metabolism during and after prolonged warm continuous blood cardioplegia (WB). DESIGN: WB was given to 21 pigs divided into three equally sized groups: WB (control), WB and GIK, or WB and glutamine. Oxidation rates of radiolabeled glucose (14C) and free fatty acid (FFA) (3H) were assessed before, during, and at 30 and 60 min after 3 h of cardiac arrest with WB. RESULTS: During standstill the substrate oxidation dropped markedly (<60%), glucose oxidation was highest in the WB + GIK group (p < 0.05) and FFA oxidation highest in the WB + glutamine group (NS). During recovery the GIK group had an elevated glucose oxidation (47 and 40% vs WB at 30 and 60 min recovery, respectively -p < 0.05). Following 30 min recovery the addition of GIK suppressed FFA oxidation some 60%. Glutamine increased the oxidation of both glucose (30%) and FFA (150%) following 60 min recovery (p < 0.05). During the whole recovery phase the relative FFA oxidation was significantly lowered in the GIK group. There were no differences between the groups regarding arterial levels or uptake of substrates, except for a higher myocardial oxygen consumption (MVO2) during cardioplegia in the glutamine group. All the hearts performed similarly. CONCLUSION: Addition of GIK or glutamine to the well-perfused and oxygenated heart during WB led to a postcardioplegic increase in oxidative metabolism and MVO2. GIK resulted in a significant metabolic shift from FFA to glucose.

Animals↗

PubMed2002

Propranolol decreases splanchnic triacylglycerol storage in burn patients receiving a high-carbohydrate diet.

OBJECTIVE: To quantify the various components of splanchnic free fatty acid and very-low-density lipoprotein-triacylglycerol (VLDL-TAG) metabolism in order to gain insight into the mechanisms responsible for the development of fatty liver in severely burned patients, and to determine if decreasing free fatty acid availability by use of propranolol could potentially reduce hepatic fatty acid accumulation. SUMMARY BACKGROUND DATA: Hepatic fat accumulation results from an imbalance between fatty acid uptake, oxidation, and release via VLDL-TAG. Fatty acid delivery is accelerated in burn patients because of stimulated lipolysis. Since propranolol decreases lipolysis, it should also decrease hepatic fatty acid uptake and thus TAG synthesis. METHODS: Stable isotope-labeled tracers and regional catheterization enabled quantification of various parameters of lipid metabolism across the splanchnic bed in severely burned patients. The acute effects of propranolol treatment were studied in all patients, and in a subgroup of patients the chronic (3 weeks) effects of propranolol were assessed. RESULTS: The rate of splanchnic uptake of palmitate was 1.68 +/- 1.3 micromol/kg/min, whereas the rates of oxidation and VLDL-TG secretion were only 0.12 +/- 0.11 and 0.003 +/- 0.02 micromol/kg/min, respectively. Propranolol significantly reduced palmitate delivery, and thus palmitate uptake, without significantly affecting oxidation or VLDL-TAG secretion. Thus, palmitate storage was reduced from 1.53 +/- 1.30 micromol/kg/min without propranolol to 0.76 +/- 0.58 micromol/kg/min after propranolol. CONCLUSIONS: Hepatic fat storage in burn patients is due to low rates of both fatty acid oxidation and VLDL-TAG secretion. Propranolol can decrease hepatic fat storage by limiting fatty acid delivery.

Adolescent↗

PubMed2002

Anabolic action of insulin on skin wound protein is augmented by exogenous amino acids.

To investigate the metabolic basis of skin wound healing, we measured in anesthetized rabbits the responses of protein kinetics in scalded skin to insulin and amino acids. L-[ring-(13)C(6)]Phe was infused on the 7th day after the ear was scalded, and the scalded ear was used as an arteriovenous unit to reflect protein kinetics in skin wound. The ipsilateral carotid artery was clamped to control the wound blood flow within four- to fivefold the normal skin rate to measure the enrichment difference in the scalded ear during hyperaminoacidemia. Neither insulin (2.5 mU x kg(-1) x min(-1)) nor amino acid (2.5 mg x kg(-1) x min(-1)) infusion alone improved net protein balance in the skin wound. In contrast, combined infusion of insulin and amino acids increased the net protein balance in skin wound from -6.5 +/- 4.5 to 1.4 +/- 5.2 micromol x 100 g(-1) x h(-1) (P < 0.01, control vs. insulin plus amino acids). We conclude that there is an interactive effect of insulin and sufficient amino acid supply on protein metabolism in skin wound, meaning that their combined anabolic effect is greater than the sum of their individual effects.

Amino Acids↗

PubMedDate not supplied

Dietary fat composition alters pulmonary function in pigs.

OBJECTIVES: We investigated the effect of various dietary fats on pulmonary surfactant composition and lung function changes that occur before and after endotoxin infusion in pigs. METHODS: Eighteen pigs were assigned to three groups (n = 6 per group) to receive a diet of protein (20% of calories), carbohydrate (20% of calories), and fat (40% of calories). In one group the fat content consisted entirely of palmitic acid. In the second group, fat came from Intralipid, which provided predominantly linoleic acid. The third group was fed fish oil. Pigs were maintained on these diets for 21 d before the experiment. Cardiovascular and pulmonary functions were determined on day 22. Pigs then were infused with endotoxin (80 mg. kg(-1). min(-1)) until the pulmonary arterial pressure reached a pressure similar to that found in trauma victims (45 to 50 mmHg). Cardiovascular and pulmonary function tests were then repeated, the animals killed, and the lungs removed for study. RESULTS: Compliance was reduced in the linoleate and fish-oil groups compared with the palmitate group before and after endotoxin. Compliance changes in pigs fed the linoleate and fish-oil diets were consistent with significant increases in lung wet:dry weight ratios, increased CO(2) retention, histologic evidence of vascular congestion, intra-alveolar edema, and alveolar septa thickening. Changes in surfactant phosphatidylcholine composition between groups were consistent with the notion that increased unsaturated fatty acids could affect surfactant function. CONCLUSIONS: We concluded that the common practice of providing calories in the form of polyunsaturated fatty acids to critically ill patients carries the risk of being detrimental to lung function.

Animals↗