Influence of surgery and experimental myocardial infarction on blood levels of free fatty acids and triiodothyronine in dogs.

Preparatory operations (PO) including thoracotomy have been performed in 11 dogs. After 6 days in 6 dogs the left anterior descending coronary artery (LAD) was ligated leading to development of acute myocardial infarction (MI). Both after PO and during MI and increase in plasma free fatty acids (FFA) and a decrease in serum triiodothyronine (T3) was observed. There was a negative correlation between T3 and FFA 4--22 hours after PO and 9--22 hours after LAD ligation. In control dogs without LAD ligation a positive correlation between FFA and T3 levels was shown 8--18 days after PO during the period of wound healing. It seems that the combination of elevated FFA and depressed T3 reflects the metabolic disturbances which are more pronounced during MI than after surgical operation connected with thoracotomy.