Dependence of calcium on thyroid hormone for the regulation of cellular functions.
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) Thyroxine-treated; 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.
Amadi
K
K
Sabo
M A
MA
Adelaiye
A B
AB
Sagay
A S
AS
D000284:Administration, Oral; D000818:Animals; D001760:Bleeding Time; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D005260:Female; D007275:Injections, Intravenous; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013965:Thyroidectomy; D013974:Thyroxine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D014599:Uterus / Q000187:drug effects / Q000502:physiology; D014914:Whole Blood Coagulation Time
D013974:Thyroxine; D002118:Calcium