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Nigerian Journal of Physiological Sciences

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Dependence of calcium on thyroid hormone for the regulation of cellular functions

AM Kemalkolam, Sabo, ABA Adelaiye, AS Sagay

Abstract


Recently, the thyroid hormone has been shown to cause increase in Ca2+concentration by mobilizing intracellular Ca2+. The mobilization of intracellular Ca2+in the absence of transmembrane Ca2+influx has been accepted as evidence for a cell-surface Ca2+ - receptor. The possible role of thyroid hormone in the regulation of cellular functions by Ca2+-channel was investigated using parameters proven to indispensably involve Ca2+: Bleeding and clotting times and rat uterine muscle activity in Ca2+-free Tyrode's solution. Adult female Wistar rats divided into four groups, namely; (i) Control, (ii) Thyroidectomized, (iii) Throidectomized-treated with thyroxine and (iv) Thyroxinetreated; were fed on rat chow. While groups i and ii were allowed access to tap water ad libitum for 60 days, groups iii and iv received tyroxine (10mg/kg body weight) every alternate day and tap water ad libitum for 60 days. All groups were kept in an air-conditioned room till they were euthanized. The results showed that thyroxine elicited biphasic contraction in Ca2+- depletion and potentiated uterine contraction during Ca2+ - loading (P<0.001). Inhibition of contractions in thyroidectomy, showed dependency of Ca2+on thyroid hormones for the regulation of cellular functions.

Keywords: thyroid hormones, calcium receptor, cellular functions

Nigerian Journal of Physiological Sciences Vol. 20(1&2) 2005: 95-100



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