Thyrotrophin, but not forskolin, increases intracellular free calcium and calmodulin in pig thyroid cells.
The effects of TSH and forskolin were examined on intracellular free calcium ([Ca2+]i) and calmodulin in normal pig thyroid cells in culture. TSH was found to produce acute increases in [Ca2+]i in pig cells. Responses were seen at concentrations of TSH between 0.01 and 10 mU/ml. Sensitivity to TSH was greater in adherent monolayers of cells than in cell suspensions and was also greater in subconfluent rather than confluent monolayers of cells. The increase in [Ca2+]i in response to TSH represented just over a doubling in [Ca2+]i whether examined at 22 degrees C or 37 degrees C. Forskolin failed to affect [Ca2+]i. TSH increased [Ca2+]i in the absence of extracellular calcium. TSH, but not forskolin, produced a significant increase in intracellular calmodulin after 3 days of culture of cells with TSH. The increase in calmodulin was of the order of 60% and did not relate to any effect of TSH on thyroid cell number.
Ye
Q L
QL
Department of Medicine, Northern General Hospital, Sheffield.
Wagner
M
M
Smythe
S
S
Mac Neil
S
S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002452:Cell Count; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology*; D008094:Lithium / Q000494:pharmacology; D018021:Lithium Chloride; D013552:Swine; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000037:antagonists & inhibitors / Q000502:physiology*
D002147:Calmodulin; D002712:Chlorides; D005576:Colforsin; D013972:Thyrotropin; D008094:Lithium; D018021:Lithium Chloride; D002118:Calcium