Thyroid hormones may influence the active transport of Ca2+ across the cell membrane. To test the physiologic relevance of this mechanism, we used inside-out human red cell membrane vesicles as a model of the cell membrane Ca2+ pump. We monitored by spectrophotometric methods the kinetics of the uptake of Ca2+ in the presence of 10-5-10-10 m thyroid hormones or their analogues. Vesicles freed of calmodulin and protein inhibitor(s) of the Ca2+ pump were also obtained. The results are as follows: (1) Thyroxine inhibits the active Ca2+ uptake; (2) this effect antagonizes that of soluble calmodulin; and (3) triiodothyronine and other analogues of the thyroid hormones are less active than thyroxine. We conclude that the thyroid hormones may influence cell Ca2+ homeostasis by direct action on the Ca2+ pump.
THYROID-HORMONES AND ACTIVE CALCIUM-TRANSPORT OF INSIDE-OUT RED-CELL MEMBRANE-VESICLES / A. RUBINACCI, P. DIVIETI, S. LODIGIANI, A. DEPONTI, M. SAMAJA. - In: BIOCHEMICAL MEDICINE AND METABOLIC BIOLOGY. - ISSN 0885-4505. - 48:3(1992), pp. 235-240.
THYROID-HORMONES AND ACTIVE CALCIUM-TRANSPORT OF INSIDE-OUT RED-CELL MEMBRANE-VESICLES
M. SAMAJAUltimo
1992
Abstract
Thyroid hormones may influence the active transport of Ca2+ across the cell membrane. To test the physiologic relevance of this mechanism, we used inside-out human red cell membrane vesicles as a model of the cell membrane Ca2+ pump. We monitored by spectrophotometric methods the kinetics of the uptake of Ca2+ in the presence of 10-5-10-10 m thyroid hormones or their analogues. Vesicles freed of calmodulin and protein inhibitor(s) of the Ca2+ pump were also obtained. The results are as follows: (1) Thyroxine inhibits the active Ca2+ uptake; (2) this effect antagonizes that of soluble calmodulin; and (3) triiodothyronine and other analogues of the thyroid hormones are less active than thyroxine. We conclude that the thyroid hormones may influence cell Ca2+ homeostasis by direct action on the Ca2+ pump.File | Dimensione | Formato | |
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