The effects of fasting and refeeding with a 'metabolic preconditioning' drink on substrate reserves and mononuclear cell mitochondrial function.
OBJECTIVE
Preoperative fasting induces metabolic stress and leads to reduced postoperative insulin sensitivity, changes attenuated by preoperative carbohydrate loading. However, the mechanisms underlying these effects remain unknown. We investigated the dynamic changes in substrate metabolism and mononuclear cell mitochondrial function after fasting followed by refeeding with a drink [ONS (Fresenius Kabi, Germany)] designed to improve metabolic function preoperatively.


METHODS
Twelve healthy volunteers took part in this study. They were fed a standardized meal and studied 4h later (baseline 'fed' state), after 12 and 24h of fasting, and 2, 4 and 6h after ingestion of ONS (contained 100g carbohydrate, 30g glutamine, and antioxidants). Changes in liver and muscle glycogen and lipids were studied using (13)C and (1)H magnetic resonance spectroscopy. The activities of mitochondrial electron transport chain complexes I, II and IV in blood mononuclear cells were measured spectrophotometrically.


RESULTS
Compared to the baseline fed state, 12 and 24h fasts led to 29% and 57% decreases (P<0.001) in liver glycogen content, respectively. Fasting for 24h decreased mitochondrial membrane complexes I (-72%, P<0.05), II (-49%, P<0.01) and IV (-41%, P<0.05) activities compared to those following a 12h fast. A 23% increase (P<0.05) in calf intramyocellular lipid (IMCL) content occurred after a 24h fast. Liver glycogen reserves increased by 47% (P<0.05) by 2h following ingestion of ONS.


CONCLUSIONS
Short-term fasting (up to 24h) affected mononuclear cell mitochondrial function adversely and increased IMCL content. Refeeding with ONS partially reversed the changes in liver glycogen.
Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre NIHR Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham NG7 2UH, UK.
Sherif
S
Awad
Mary C
MC
Stephenson
Elisa
E
Placidi
Luca
L
Marciani
Dumitru
D
Constantin-Teodosiu
Penny A
PA
Gowland
Robin C
RC
Spiller
Kenneth C H
KC
Fearon
Peter G
PG
Morris
Ian A
IA
Macdonald
Dileep N
DN
Lobo
D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage; D001628:Beverages; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D019587:Dietary Supplements; D004435:Eating / Q000502:physiology*; D045222:Electron Transport Chain Complex Proteins; D005215:Fasting / Q000009:adverse effects / Q000502:physiology*; D005973:Glutamine / Q000008:administration & dosage; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology*; D050356:Lipid Metabolism; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D008297:Male; D055442:Metabolome; D008928:Mitochondria / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000378:metabolism; D009929:Organ Size; D019990:Perioperative Care / Q000379:methods; D013997:Time Factors; D055815:Young Adult
D000975:Antioxidants; D004040:Dietary Carbohydrates; D045222:Electron Transport Chain Complex Proteins; D005973:Glutamine; D006003:Glycogen