Thyroid hormone (TH) levels increase in the postnatal life and are essential for maturation of myocardial Ca2+ handling. During this time, the sarcolemmal (SL) Na+/Ca2+ exchanger (NCX) function decreases and the sarcoendoplasmic reticulum (SR) Ca2+-ATPase (SERCA2) function increases. We examined the effects of postnatal hypo- or hyperthyroidism on NCX and SERCA2 in rat hearts. Animals were rendered hypothyroid by 0.05% 6-n-propyl-2-thiouracil in drinking water given to nursing mothers from days 2 to 21 postpartum. Hyperthyroidism was induced by daily injections of 10 microg/100 g body weight of 3,3',5-triiodo-L-thyronine during this period. Ventricular steady-state mRNA and protein levels of NCX and SERCA2 were analyzed by Northern and Western blotting. These were compared with SL Na+ gradient-induced and SR oxalate-supported Ca2+ transports in isolated membranes. In hypothyroidism, NCX mRNA and protein were elevated by 66 and 80%, respectively, and SERCA2 mRNA and protein were reduced to 55 and 70%, respectively (P < 0.05 vs. euthyroid). Corresponding differences were observed in the respective Ca2+ transports. Conversely, reduced NCX (by 50%) and elevated SERCA2 (by 150%) activities were found in hyperthyroidism (P < 0.05). The levels of NCX and SERCA2 mRNA and protein were, however, unchanged in hyperthyroidism, indicating that functional changes are not due to altered NCX and SERCA2 expression. In this case, a decline in noninhibitory phosphorylated phospholamban is a likely explanation for the elevated SR Ca2+ transport. In conclusion, physiological TH levels appear to be essential for normal reciprocal changes in the expression and function of myocardial NCX and SERCA2 during postnatal development.

• MeSH
• Ca2+-ATPasy biosyntéza   MeSH
• genetická transkripce účinky léků   MeSH
• hypertyreóza chemicky indukované   metabolismus   patofyziologie   MeSH
• hypotyreóza chemicky indukované   metabolismus   patofyziologie   MeSH
• krysa rodu Rattus MeSH
• membránové proteiny metabolismus   MeSH
• messenger RNA biosyntéza   MeSH
• myokard metabolismus   MeSH
• novorozená zvířata MeSH
• potkani Wistar MeSH
• propylthiouracil farmakologie   MeSH
• proteiny vázající vápník biosyntéza   MeSH
• pumpa pro výměnu sodíku a vápníku biosyntéza   MeSH
• regresní analýza MeSH
• sarkolema metabolismus   MeSH
• sarkoplazmatické retikulum enzymologie   MeSH
• srdce růst a vývoj   MeSH
• štítná žláza fyziologie   MeSH
• trijodthyronin farmakologie   MeSH
• vývojová regulace genové exprese * účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Ca2+-ATPasy MeSH
• membránové proteiny MeSH
• messenger RNA MeSH
• phospholamban MeSH Prohlížeč
• propylthiouracil MeSH
• proteiny vázající vápník MeSH
• pumpa pro výměnu sodíku a vápníku MeSH
• trijodthyronin MeSH