Effects of in vitro physicochemical factors on hormone-depositing capacity of human erythrocytes

Abstract

Effects of ultraviolet radiation and pH of isotonic protein-free solution on erythrocyte capacity to deposit thyroid hormones were studied in specimens of venous blood from men aged 20- 35 years. Ultraviolet irradiation of the blood led to a dose-dependent increase in the plasma triiodothyronin concentration, the concentration of thyroxin remaining unchanged. Incubation of human erythrocytes in phosphate buffers (0.15 M) led to a sharp increase in the concentrations of triiodothyronin and thyroxin in incubation media, the concentration of triiodothyronin depending on the medium pH and the lowest increment in its concentration being observed at pH 6.0. The concentration of thyroxin in buffer solutions surpassed the hormone concentration in the plasma more than 7-fold and did not depend on pH of the medium. Results of ultraviolet exposure of the blood and erythrocyte incubation in buffer solutions suggest that mechanisms of thyroid hormone deposition in erythrocytes are concerned with regulation of mainly triiodothyronin but not thyroxin.