Myocardial uptake and release of substrates in type II diabetics undergoing coronary surgery.
OBJECTIVE
Knowledge about myocardial metabolism in diabetic patients is limited, and even more so in association with myocardial ischaemia and cardiac surgery. This study investigates myocardial substrate utilization in type II diabetic patients after elective coronary artery bypass graft surgery (CABG).


METHODS
Myocardial substrate utilization in 10 type II diabetic patients was assessed during the first hours after elective CABG with the coronary sinus catheter technique.


RESULTS
No significant myocardial uptake of carbohydrates was observed. Free fatty acids were extracted throughout the study period but uptake was not related to arterial levels. As arterial levels of beta-hydroxybutyric acid tended to increase a significant myocardial uptake emerged. The average extraction rate of beta-hydroxybutyric acid was 31% with a peak of 42%. A comparable extraction rate of glutamate was also found whereas alanine was released from the heart.


CONCLUSIONS
Free fatty acids were the main source of energy for the heart whereas uptake of carbohydrates was restricted. The high extraction rates of beta-hydroxybutyric acid and glutamate suggest an adaptive role for these substrates during this unfavourable metabolic state for the post-ischaemic diabetic heart.
Szabó
Z
Z
Department of Cardiothoracic Anaesthesia, Linköping Heart Centre, University Hospital, Sweden. Zoltan.Szabo@lio.se
Håkanson
E
E
Jorfeldt
L
L
Svedjeholm
R
R
D020155:3-Hydroxybutyric Acid / Q000097:blood; D001026:Coronary Artery Bypass; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000503:physiopathology / Q000601:surgery*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005990:Glycerol / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D019990:Perioperative Care; D011300:Preoperative Care
D005230:Fatty Acids, Nonesterified; D005990:Glycerol; D020155:3-Hydroxybutyric Acid