title: Thyroid hormone increased L-type calcium channel mRNA expression and L-type calcium current of myocytes in rabbits.
abstract: OBJECTIVE
  To investigate the effects of thyroid hormone on L-type calcium channel mRNA and L-type calcium current of atrium and ventricle.
  
  
  METHODS
  Sixteen New Zealand white rabbits were randomized into Thyroxine group (n=8) and Control group (n=8). In Throxine group, rabbits were injected intraperitoneally with L-thyroxine solution for 2 weeks (1 mg/kg·d(-1)) to induce hyperthyroidism. In Control group, rabbits were injected with the same volume of saline as for Thyroxine group. On day 15, 4 rabbits in each group were killed randomly to exam the L-type calcium current of atrium and ventricle using whole cell patch clamp; the other 4 rabbits were killed to detect the expression of L-type calcium channel mRNA using RT-PCR.
  
  
  RESULTS
  The mean peak of L-type calcium current densities (pA/pF) at -10 mV was higher in Thyroxine group than in Control group (-8.59±0.68 vs. -6.54±0.49 in atrium, n=8, p<0.001; -9.24±0.67 vs. -7.06±0.21 in ventricle, n=8, p<0.001). L-calcium channel mRNA expression of both atrial myocytes and ventricular cells in Thyroxine group was significantly higher than those in Control group (p<0.05).
  
  
  CONCLUSIONS
  Extrinsic thyroid hormone increased expression of L-type calcium channel mRNA and ICa,L current densities in both atrium and ventricle. These changes infer that supplement of thyroid hormone may ameliorate myocardial contraction in some special conditions such as sepsis.
authors: Department of Critical Care Medicine, Renmin Hospital of Wuhan University, Wuhan, China. doctoryu@yahoo.cn
authors: Zhui
authors: Z
authors: Yu
authors: Teng
authors: T
authors: Wang
authors: Lin
authors: L
authors: Xu
authors: Cong-xin
authors: CX
authors: Huang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D006325:Heart Atria / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006980:Hyperthyroidism / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000235:genetics*; D011817:Rabbits; D018805:Sepsis / Q000188:drug therapy; D013963:Thyroid Hormones / Q000378:metabolism / Q000494:pharmacology; D013974:Thyroxine / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D020746:Calcium Channels, L-Type; D012333:RNA, Messenger; D013963:Thyroid Hormones; D013974:Thyroxine; D002118:Calcium