Thyroid hormone may induce changes in the concentration of the mitochondrial calcium uniporter.
We explored the possibility that the hormone 3,3',5-tri-iodothyronine can regulate the biosynthesis of the mitochondrial calcium uniporter. To meet this objective experiments on Ca(2+) transport, and binding of the specific inhibitor Ru(360) were carried out in mitochondria isolated from euthyroid, hyperthyroid and hypothyroid rats. It was found that V(max) for Ca(2+) transport increased from 11.67+/-0.8 in euthyroid to 14.36+/-0.44 in hyperthyroid, and decreased in hypothyroid mitochondria to 8.62+/-0.63 nmol Ca(2+)/mg/s. Furthermore, the K(i) for the specific inhibitor Ru(360), depends on the thyroid status, i.e. 18, 19 and 13 nM for control, hyper- and hypothyroid mitochondria, respectively. In addition, the binding of 103Ru(360) was increased in hyperthyroid and decreased in hypothyroid mitochondria. Scatchard analysis for the binding of 103Ru(360) showed the following values: 28, 40 and 23 pmol/mg for control, hyper- and hypothyroid mitochondria, respectively. The K(d) for 103Ru(360) was found to be 30.39, 37.03 and 35.71 nM for controls, hyper- and hypothyroid groups, respectively. When hypothyroid rats were treated with thyroid hormone, mitochondrial Ca(2+) transport, as well as 103Ru(360) binding, reached similar values to those found for euthyroid mitochondria.
Robles
Sandra G
SG
Departamento de Bioquímica, Instituto Nacional de Cardiología, Ignacio Chávez, Juan Badiano # 1 Tlalpan, México, D.F. 014080, Mexico.
Franco
Martha
M
Zazueta
Cecilia
C
García
Noemí
N
Correa
Francisco
F
García
Gerardo
G
Chávez
Edmundo
E
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D004734:Energy Metabolism; D006980:Hyperthyroidism / Q000378:metabolism; D007037:Hypothyroidism / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017975:Ruthenium Compounds / Q000737:chemistry; D014284:Triiodothyronine / Q000494:pharmacology / Q000502:physiology*
D015220:Calcium Channels; D002135:Calcium-Binding Proteins; C112020:Ru 360; D017975:Ruthenium Compounds; C034703:mitochondrial calcium uniporter; D014284:Triiodothyronine; D002118:Calcium