INCREASED RATIO BETWEEN ANAEROBIC AND AEROBIC METABOLISM IN LYMPHOCYTES FROM HYPERTHYROID PATIENTS

While an increased oxygen consumption is accepted as one consequence o f hyperthyroidism, only few data are available on the role of anaerobi c processes for the increased metabolic activity in this disease. In t his study we evaluated the relative importance of anaerobic and aerobi c metabolism for the metabolic activity in lymphocytes from patients b efore and after treatment for hyperthyroidism. Total lymphocyte heat p roduction rate (P), reflecting total cell metabolic activity, was dete rmined in a plasma lymphocyte suspension using direct microcalorimetry . The contribution from aerobic metabolism (O-2 - P) was calculated fr om the product of the lymphocyte oxygen consumption rate and the entha lpy change for glucose combustion, and the anaerobic contribution as t he difference between P and O-2 - P. The total lymphocyte heat product ion rate P was 3.37 +/- 0.25 (SEM) pW/cell (N = 11) before and 2.50 +/ - 0.11 pW/cell (N = 10) after treatment for hyperthyroidism (p < 0.01) as compared to 2.32 +/- 0.10 pW/cell in a control group (N = 18). The aerobic component O-2 - P amounted to 1.83 +/- 0.11 pW/cell in the pa tient group before and 1.83 +/- 0.08 pW/cell after treatment and to 1. 71 +/- 0.16 pW/cell in 10 controls. Out of P, the O-2 - P component co rresponded to 56.8 +/- 4.4% in the hyperthyroid state and to 73.7 +/- 3.2% after treatment (p < 0.01) as compared to 73.4 +/- 4.4% in the 10 euthyroid controls. It was concluded that the increased metabolic act ivity demonstrated in lymphocytes from hyperthyroid patients cannot be explained by an increased oxygen-dependent consumption. This suggests that cell function may be comparatively more dependent on anaerobic m etabolism during thyroid hormone excess and that adenosine triphosphat e generation thereby has to be supplied through an increased metabolis m of energy-rich substrates along anaerobic metabolic pathways.