Metabolic Characteristics of Preparations of Isolated Sheep Thyroid Gland Cells. II. Fatty Acid Oxidation

The utilization of albuminbound palmitic acid-1-¹⁴C, 6-¹⁴C, 11-¹⁴C and 13-¹⁴C by isolated sheep thyroid cells and by slices of the gland was studied.

1. The ¹⁴C of palmitic acid-1-^l4C was incorporated into cholesterol esters, triglycerides and phospholipids, but ¹⁴CO₂ was the major end-product.

2. The results obtained with the variously labeled fatty acids show that the thyroid cell per se is capable of disrupting the fatty acid molecule to completion.

3. The conversion of the ¹⁴C of palmitic acid-1-¹⁴C to ¹⁴CO₂ was 1.6-2.8 times that observed with palmitic acid-6-¹⁴C. This is explained by the isotope dilution scheme previously proposed for the operation of the Krebs cycle.

4. Three hundred mg of isolated cells converted at least twice as much of the ¹⁴C of palmitic acid-1-¹⁴C to CO₂ as did 400 mg of the slices. (Endocrinology77: 103, 1965)