Mechanism of Thyroid Calorigenesis: Role of Active Sodium Transport
Abstract
The hypothesis that thyroid calorigenesis is mediated by stimulation of active Na+ transport was tested by measuring the Qo2 of liver slices and skeletal muscle (diaphragm) from thyroxine- and triiodothyronine-injected thyroidectomized and normal rats in media fortified with ouabain (10-3 M) and/or free of Na+ or K+. In both tissues, more than 90% of the increase in Qo2 produced by injections of thyroid hormone in euthyroid rats was derived from increased energy utilization by the Na+ pump. In triiodothyronine-treated thyroidectomized rats, activation of Na+ transport accounted for 90% or more of the increment in Qo2 in liver and 40% or more of the increment in diaphragm. Intracellular Na+, K+, and Cl- concentrations were measured in euthyroid and hyperthyroid liver and diaphragm. The transmembrane Na+ and K+ concentration differences were significantly increased in both tissues by the administration of triiodothyronine. These results indicate that thyroid hormone activates Na+ extrusion and K+ accumulation either by increasing the local concentration of ATP or by direct stimulation of the Na+ pump.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- October 1970
- DOI:
- 10.1073/pnas.67.2.1071
- Bibcode:
- 1970PNAS...67.1071I