Increased lymphocyte thermogenesis in hyperthyroid patients. Role of Na/K pump function. Evaluation of aerobic/anaerobic metabolism.
The role of the Na/K pump for the increased cell energy expenditure in hyperthyroidism was studied by measuring total lymphocyte heat production rate in samples with and without ouabain inhibition of Na/K ATP-ase. In addition, the relative contribution of aerobic processes to lymphocyte thermogenesis was calculated from oxygen consumption measurements. In 12 patients with clinical and laboratory hyperthyroidism total lymphocyte heat production rate was 3.19 +/- 0.21 pW/cell, significantly higher than in 7 patients with subclinical hyperthyroidism (2.14 +/- 0.11 pW/cell) and in 15 euthyroid subjects (2.26 +/- 0.11 pW/cell) (p less than 0.001). The relative decrease in lymphocyte heat production rate after ouabain, giving a quantitative measure of the activity of the Na/K ATP-ase and reflecting the importance of Na/K pump function for the overall rate of lymphocyte metabolism, was not significantly different between the groups: 19.5 +/- 3.6% in hyperthyroid patients, 14.2 +/- 2.3% in subclinical hyperthyroid patients and 17.8 +/- 3.1% in euthyroid subjects. According to the rate of lymphocyte oxygen consumption, aerobic processes represented 58.4 +/- 6.7% of total lymphocyte energy expenditure in hyperthyroid patients, not significantly different from subclinical hyperthyroidism (62.6 +/- 8.4%) or from euthyroidism (66.6 +/- 2.7%). These data do not support the hypothesis of a specific role of the Na/K pump function for the increased cell thermogenesis in hyperthyroidism and indicate a parallel stimulation of aerobic and anaerobic processes by thyroid hormone excess.
Valdemarsson
S
S
Department of Internal Medicine, University Hospital of Lund, Sweden.
Ikomi-Kumm
J
J
Monti
M
M
D000328:Adult; D000332:Aerobiosis; D000368:Aged; D000693:Anaerobiosis; D001833:Body Temperature Regulation; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008214:Lymphocytes / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology
D000254:Sodium-Potassium-Exchanging ATPase