Myocardial metabolism 8 hours after coronary surgery: effects of dopamine.
Myocardial substrate metabolism is abnormal in the early period after cardiac surgery. Myocardial uptake of substrates remains restricted 6 hours postoperatively and cannot match the demand during periods of increased energy requirements. We investigated the relationship between myocardial oxidative rate and substrate uptake in 22 men c. 8 hours after coronary surgery. Myocardial energy demand was raised experimentally by infusing dopamine. The influence of selective beta 1-blockade was analyzed. The uptake of free fatty acids dominated (34.74 +/- 8.83 mmol/min*10(-3) and sufficed to explain the oxygen consumption in basal postoperative conditions (0.468 +/- 0.051 mumol/min) and during amplified energy requirements (0.881 +/- 0.117, r = 0.71). Although the capacity to adjust substrate uptake to energy requirements thus was regained, the uptake of glucose and of lactate (6.14 +/- 13.13 and 2.29 +/- 20.31 mmol/min*10(3) respectively) was marginal, which may be important for ischaemic tolerance. Metoprolol influenced oxygen consumption during amplified adrenergic activity, but did not markedly affect substrates.
Thorelius
J
J
Department of Thoracic and Cardiovascular Surgery, University Hospital, Uppsala, Sweden.
Ekroth
R
R
Joachimsson
P O
PO
van der Linden
J
J
Ronquist
G
G
Tyden
H
H
Wesslén
O
O
D001026:Coronary Artery Bypass; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D004562:Electrocardiography; D004734:Energy Metabolism / Q000187:drug effects; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007262:Infusions, Intravenous; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D013997:Time Factors
D005230:Fatty Acids, Nonesterified; D007773:Lactates; D019344:Lactic Acid; D008790:Metoprolol; D005947:Glucose; D004298:Dopamine