Peripheral effects of thyroid hormones: Alteration of intracellular Na-concentration, ouabain-sensitive Na-transport, and Na-Li countertransport in human red blood cells

Abstract

To investigate the effect of thyroid hormones on erythrocyte cation transport systems and intracellular electrolyte content we have measured the activity of Na-K ATPase, Na-Li countertransport, as well as red cell sodium and potassium contents in patients with hyperthyroidism and in euthyroid controls. Intracellular Na- and K-concentrations were determined in erythrocytes washed three times in isotonic MgCl2 solution. Ouabain-sensitive Na-transport was estimated as the increase of Na before and after addition of ouabain in an erythrocyte suspension in isotonic Na-free medium. Na-Li countertransport was measured according to the method described by Canessa et al. [2]. The patients with hyperthyroidism exhibited a significantly elevated intracellular sodium content as well as a highly increased Na-K ATPase activity. Intracellular potassium content was not altered in the hyperthyroid subjects, but Na-Li countertransport was markedly decreased as compared to the controls. The results indicate that different ion transport systems of the erythrocyte membrane are influenced by thyroid hormones. We suggest that the elevation of Na-K ATPase activity might be due to the increased intracellular sodium concentration which is caused by the diminished countertransport pathway. Furthermore, the activity of Na-K ATPase, Na-Li countertransport, and intracellular sodium content in erythrocytes might be a useful peripheral indicator of thyroid hormone excess.

EFFECTS OF OXIDATIVE STRESS ON THE ERYTHROCYTE Na+,K+ATPase ACTIVITY IN FEMALE HYPERTHYROID PATIENTS

“…In hyperthyroidism it has been suggested that (1) the increase in membrane permeability (Rubython et al, 1983), (2) change in lipid composition of the membrane (Cole & Waddell, 1976), or (3) elevated protein catabolism is responsible for decreased Na + ,K + -ATPase activity in hyperthyroidism. In contrast, elevated Na + ,K + -ATPase activity was reported by Sutterlin et al (1984) and Yoon et al (1989). Our findings indicate that the pump activity may be decreased due to enhanced freeradical-induced membrane damage.…”

Interrelations between Lithium Therapy, Auto-Immune Thyroiditis and TSH

“…With regard to the thyroid function, erythrocyte LSC activity was significantly lower in patients with low TSH level among a group of lithium-treated bipolar patients [15]. In the same line the excess of thyroid hormones in hyperthyroidical patients has been suggested [18] to be responsible for the depression of the LSC and consequently for an increase of the LR.…”

Hastalıkların Fizyopatolojisinde Eritrosit Deformabilitesinin Önemi

“…Sutterlin ve ark. ise eritrosit memranı Na-K ATPaz aktiviteside artış olduğunu gözlemlemiştir 42 . Yapılan çalışmalarda tiroid hormonlarının etkisiyle kırmızı hücre filtrelenebilirliğinde açıkça bir azalma meydana geldiği ortaya konulmaktadır.…”