Abstract
In rats with hypothyroidism caused by partial thyroidectomy, a significant decrease in mitochondrial electron-transport activity was found 6 weeks after the thyroidectomy. The level of acetylcholine in heart muscle cells of the left ventricle was found to be increased at the same time after the operation. Norepinephrine in the same cells increased even earlier; significant increase was found 3 weeks after the operation. Supplementation with triiodothyronine lessened these impairments. The relationship among these changes was discussed in relation to hypothyroid cardiomyopathy.
